ci: update pinned Action SHAs to current latest versions

The previous commit pinned actions to commit SHAs but used stale
version tags (v4.2.2, v2.7.5, old nextest/cargo-llvm-cov refs).
Update to the actual current HEAD of each pinned tag:

  actions/checkout        v4.2.2 → v4.3.1  (34e114876b0b...)
  Swatinem/rust-cache     v2.7.5 → v2.9.1  (c19371144df3...)
  taiki-e/install-action  nextest           (56cc9adf3a3e...)
  taiki-e/install-action  cargo-llvm-cov    (e4b3a0453201...)

actions-rs/toolchain, actions-rs/clippy-check, and
codecov/codecov-action SHAs were already correct.

https://claude.ai/code/session_01VD7Bo8upj3cQwWDf9ni2Ln

Author: claude

.github/workflows/coverage.yml

@@ -20,11 +20,11 @@ jobs:
       contents: read
 
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
       - name: Install Rust
         run: rustup toolchain install nightly-2025-12-01 --profile minimal --component llvm-tools-preview
-      - uses: Swatinem/rust-cache@82a92a6e8fbeee089604da2575dc567ae9ddeaab # v2.7.5
-      - uses: taiki-e/install-action@af00f4b4a828581905c69e668cd067c8dad0578a # cargo-llvm-cov
+      - uses: Swatinem/rust-cache@c19371144df3bb44fab255c43d04cbc2ab54d1c4 # v2.9.1
+      - uses: taiki-e/install-action@e4b3a0453201addddc06d3a72db90326aad87084 # cargo-llvm-cov
       - name: Generate code coverage
         run: cargo +nightly-2025-12-01 llvm-cov --all-features --workspace --doctests --lcov --output-path lcov.info
       - name: Upload coverage to Codecov

.github/workflows/long_running.yml

@@ -25,7 +25,7 @@ jobs:
       contents: read
 
     steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
     - name: Install stable
       uses: actions-rs/toolchain@16499b5e05bf2e26879000db0c1d13f7e13fa3af # v1.0.7
       with:

.github/workflows/test.yml

@@ -27,7 +27,7 @@ jobs:
       checks: write
 
     steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
 
     - name: Install nightly
       uses: actions-rs/toolchain@16499b5e05bf2e26879000db0c1d13f7e13fa3af # v1.0.7
@@ -42,7 +42,7 @@ jobs:
             profile: minimal
             components: clippy
 
-    - uses: Swatinem/rust-cache@82a92a6e8fbeee089604da2575dc567ae9ddeaab # v2.7.5
+    - uses: Swatinem/rust-cache@c19371144df3bb44fab255c43d04cbc2ab54d1c4 # v2.9.1
 
     - name: Check Formatting
       run: cargo +nightly fmt --all -- --check
@@ -77,7 +77,7 @@ jobs:
     name: test-${{ matrix.features.label}}
 
     steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
 
     - name: Install stable
       uses: actions-rs/toolchain@16499b5e05bf2e26879000db0c1d13f7e13fa3af # v1.0.7
@@ -86,8 +86,8 @@ jobs:
             profile: minimal
             override: true
 
-    - uses: taiki-e/install-action@ed90ac8c92bcd626a952a160afa50dfe66ca557c # nextest
-    - uses: Swatinem/rust-cache@82a92a6e8fbeee089604da2575dc567ae9ddeaab # v2.7.5
+    - uses: taiki-e/install-action@56cc9adf3a3e2c23eafb56e8acaf9d0373cb845a # nextest
+    - uses: Swatinem/rust-cache@c19371144df3bb44fab255c43d04cbc2ab54d1c4 # v2.9.1
 
     - name: Run tests
       run: |