Add wheel installation step to CI workflow and update cache creation logic

Author: arash77

.github/workflows/pr.yaml

@@ -72,6 +72,10 @@ jobs:
       with:
         path: ~/.planemo
         key: planemo_cache_py_${{ matrix.python-version }}_gxy_${{ steps.get-galaxy-sha.outputs.galaxy-head-sha }}
+    # Install the `wheel` package so that when installing other packages which
+    # are not available as wheels, pip will build a wheel for them, which can be cached.
+    - name: Install wheel
+      run: pip install wheel
     - name: Update galaxy packages to match tested Galaxy version
       run: |
         base="git+https://github.com/${{ env.GALAXY_FORK }}/galaxy.git@${{ env.GALAXY_BRANCH }}#subdirectory=packages"
@@ -86,7 +90,7 @@ jobs:
       uses: galaxyproject/planemo-ci-action@v1
       id: discover
       with:
-        create-cache: ${{ steps.cache-planemo.outputs.cache-hit != 'true' }}
+        create-cache: ${{ steps.cache-pip.outputs.cache-hit != 'true' || steps.cache-planemo.outputs.cache-hit != 'true' }}
         galaxy-fork: ${{ env.GALAXY_FORK }}
         galaxy-branch: ${{ env.GALAXY_BRANCH }}
         max-chunks: ${{ env.MAX_CHUNKS }}