ci: reenable cron job

to run on december 31

.github/workflows/cron-update-rust.yml

@@ -1,40 +1,40 @@
-# name: Update rust version
-# on:
-#   schedule:
-#     - cron: "0 0 15 * *" # At 00:00 on day-of-month 15.
-#   workflow_dispatch: # allows manual triggering
-# jobs:
-#   format:
-#     name: Update stable rustc
-#     runs-on: ubuntu-latest
-#     steps:
-#       - uses: actions/checkout@v4
-#       - uses: dtolnay/rust-toolchain@stable
-#       - name: Update rust.yml to use latest stable
-#         run: |
-#           set -x
-#           # Extract the date from whatever version of the compiler dtolnay/rust-toolchain gives us.
-#           RUST_VERSION=$(rustc --verbose --version | sed -ne 's/^release: //p')
-#           # Update the version in the reference file.
-#           echo "${RUST_VERSION}" > rust-version
-#           echo "rust_version=${RUST_VERSION}" >> $GITHUB_ENV
-#           # In case of no new version don't make an empty PR.
-#           if ! git diff --exit-code > /dev/null; then
-#               echo "Updated rustc. Opening PR."
-#               echo "changes_made=true" >> $GITHUB_ENV
-#           else
-#               echo "Attempted to update rustc but the latest stable date did not change. Not opening any PR."
-#               echo "changes_made=false" >> $GITHUB_ENV
-#           fi
-#       - name: Create Pull Request
-#         if: env.changes_made == 'true'
-#         uses: peter-evans/create-pull-request@v6
-#         with:
-#           token: ${{ secrets.CREATE_PR_TOKEN }}
-#           author: Update Rustc Bot <bot@example.com>
-#           committer: Update Rustc Bot <bot@example.com>
-#           title: Automated weekly update to rustc (to ${{ env.rust_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 ${{ env.rust_version }}
-#           branch: create-pull-request/weekly-stable-update
+name: Update rust version
+on:
+  schedule:
+    - cron: "0 0 31 12 *" # At 00:00 on day-of-month 31 in Dec.
+  workflow_dispatch: # allows manual triggering
+jobs:
+  format:
+    name: Update stable rustc
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - name: Update rust.yml to use latest stable
+        run: |
+          set -x
+          # Extract the date from whatever version of the compiler dtolnay/rust-toolchain gives us.
+          RUST_VERSION=$(rustc --verbose --version | sed -ne 's/^release: //p')
+          # Update the version in the reference file.
+          echo "${RUST_VERSION}" > rust-version
+          echo "rust_version=${RUST_VERSION}" >> $GITHUB_ENV
+          # In case of no new version don't make an empty PR.
+          if ! git diff --exit-code > /dev/null; then
+              echo "Updated rustc. Opening PR."
+              echo "changes_made=true" >> $GITHUB_ENV
+          else
+              echo "Attempted to update rustc but the latest stable date did not change. Not opening any PR."
+              echo "changes_made=false" >> $GITHUB_ENV
+          fi
+      - name: Create Pull Request
+        if: env.changes_made == 'true'
+        uses: peter-evans/create-pull-request@v6
+        with:
+          token: ${{ secrets.CREATE_PR_TOKEN }}
+          author: Update Rustc Bot <bot@example.com>
+          committer: Update Rustc Bot <bot@example.com>
+          title: Automated weekly update to rustc (to ${{ env.rust_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 ${{ env.rust_version }}
+          branch: create-pull-request/weekly-stable-update