cron-weekly-update: copy toolchain update files from rust-bitcoin

With the move to the latest cargo-rbmt we have replaced our nightly-version
files with Cargo.toml entries. Update the cronjob accordingly, and add a
new one for the stable compiler version.

This moves the update date from Mondays to Saturdays.

It's a bit nicer to have Saturday, both because this is the same time as all
the other rust-bitcoin PRs are opened so I can bulk-review them, but also
because it means I can merge these (usually trivial) PRs on Sunday and not
have them mixed up with activity during the workweek.

Author: apoelstra

.github/workflows/cron-weekly-update-nightly.yml

@@ -1,41 +1,35 @@
 name: Update Nightly rustc
 on:
   schedule:
-    - cron: "5 0 * * 1" # runs every Monday at 00:05 UTC
+    - cron: "5 0 * * 6" # Saturday at 00:05
   workflow_dispatch: # allows manual triggering
+permissions: {}
 jobs:
   format:
     name: Update nightly rustc
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: write
+      id-token: write
+      pull-requests: write
     steps:
-      - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@nightly
-      - name: Update rust.yml to use latest nightly
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
+      - name: Install cargo-rbmt
+        run: cargo install --git https://github.com/rust-bitcoin/rust-bitcoin-maintainer-tools.git --rev $(cat rbmt-version) cargo-rbmt
+      - name: Update nightly toolchain in Cargo.toml
         run: |
-          set -x
-          # Not every night has a nightly, so extract the date from whatever
-          # version of the compiler dtolnay/rust-toolchain gives us.
-          NIGHTLY_DATE=$(rustc +nightly --verbose --version | sed -ne 's/^commit-date: //p')
-          # Update the nightly version in the reference file.
-          echo "nightly-${NIGHTLY_DATE}" > nightly-version
-          echo "nightly_date=${NIGHTLY_DATE}" >> $GITHUB_ENV
-          # Some days there is no new nightly. In this case don't make an empty PR.
-          if ! git diff --exit-code > /dev/null; then
-              echo "Updated nightly. Opening PR."
-              echo "changes_made=true" >> $GITHUB_ENV
-          else
-              echo "Attempted to update nightly but the latest-nightly date did not change. Not opening any PR."
-              echo "changes_made=false" >> $GITHUB_ENV
-          fi
+          eval "$(cargo rbmt toolchains --update-nightly)"
+          echo "nightly_version=$RBMT_NIGHTLY" >> $GITHUB_ENV
       - name: Create Pull Request
-        if: env.changes_made == 'true'
-        uses: peter-evans/create-pull-request@v6
+        uses: peter-evans/create-pull-request@271a8d0340265f705b14b6d32b9829c1cb33d45e # v7.0.8
         with:
           token: ${{ secrets.APOELSTRA_CREATE_PR_TOKEN }}
           author: Update Nightly Rustc Bot <bot@example.com>
           committer: Update Nightly Rustc Bot <bot@example.com>
-          title: Automated daily update to rustc (to nightly-${{ env.nightly_date }})
+          title: Automated daily update to rustc (to ${{ env.nightly_version }})
           body: |
-           Automated update to Github CI workflow `rust.yml` by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action
-          commit-message: Automated update to Github CI to rustc nightly-${{ env.nightly_date }}
+           Automated update to Cargo.toml workspace metadata by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action
+          commit-message: Automated update to rustc ${{ env.nightly_version }}
           branch: create-pull-request/daily-nightly-update

.github/workflows/cron-weekly-update-stable.yml

@@ -0,0 +1,34 @@
+name: Update Stable rustc
+on:
+  schedule:
+    - cron: "0 0 * * 5" # runs every Friday at 00:00 (generally rust releases on Thursday)
+  workflow_dispatch: # allows manual triggering
+permissions: {}
+jobs:
+  format:
+    name: Update stable rustc
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
+      - name: Install cargo-rbmt
+        run: cargo install --git https://github.com/rust-bitcoin/rust-bitcoin-maintainer-tools.git --rev $(cat rbmt-version) cargo-rbmt
+      - name: Update stable toolchain in Cargo.toml
+        run: |
+          eval "$(cargo rbmt toolchains --update-stable)"
+          echo "stable_version=$RBMT_STABLE" >> $GITHUB_ENV
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@271a8d0340265f705b14b6d32b9829c1cb33d45e # v7.0.8
+        with:
+          token: ${{ secrets.APOELSTRA_CREATE_PR_TOKEN }}
+          author: Update Stable Rustc Bot <bot@example.com>
+          committer: Update Stable Rustc Bot <bot@example.com>
+          title: Automated weekly update to rustc stable (to ${{ env.stable_version }})
+          body: |
+           Automated update to Cargo.toml workspace metadata by [create-pull-request](https://github.com/peter-evans/create-pull-request) GitHub action
+          commit-message: Automated update to rustc stable-${{ env.stable_version }}
+          branch: create-pull-request/weekly-stable-update