Have the action output a versioning element so it could be used as part of the cache restore key (#239)

* Do a bit of YAMLlint'ing

* Ease consumer cache invalidation

By providing an output with the action version we ease
cache invalidation on consumer, due to the fact we can
now stop worrying about changes to the action's cache itself

Might also be interesting for self-hosted runners...

* Remove duplicates

* Do further validations for robustness

.github/workflows/action.yml

@@ -7,6 +7,31 @@ env:
   GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
 
 jobs:
+  version:
+    name: Version with commit unique id
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main'
+    steps:
+      - uses: actions/checkout@v3
+      - name: Version it!
+        run: |
+          # We expect a string such as const setupBeamVersion = 'undefined' in the code
+          SHA=$(git rev-parse --short HEAD)
+          sed -i'.bak' \
+              -e "s/const setupBeamVersion = '.*'/const setupBeamVersion = '${SHA}'/g" \
+              dist/index.js
+          # it always starts by being 'undefined'
+          NEWVER=$(grep -oE "const setupBeamVersion = '.*'" dist/index.js | cut -d\' -f2)
+          if [ "$NEWVER" == "undefined" ]; then
+              exit 1
+          else
+              echo "Continuing... new version is ${NEWVER}"
+          fi
+          git config user.name "GitHub Actions"
+          git config user.email "actions@user.noreply.github.com"
+          git add dist/index.js
+          git commit -m "Update setup-beam version output to ${SHA}"
+          git push origin main
   check_integrity:
     name: Expected local npm actions
     runs-on: ubuntu-latest