COMP: Add Github workflow for keeping pre-commit configuration up-to-…

…date

This commit introduces a GitHub workflow specifically designed to keep the
pre-commit configuration current. It leverages the credentials of the
"Slicer GitHub App" associated with the Slicer organization.

The decision to opt for a dedicated workflow over granting access to the
pre-commit.ci service was made to ensure a tested and adaptable solution.
By adopting this approach, we pave the way for potential reuse of the workflow
in custom applications hosted privately.

.github/workflows/pre-commit-autoupdate.yml

@@ -0,0 +1,87 @@
+name: Pre-commit auto-update
+
+on:
+  # every day at midnight
+  schedule:
+    - cron: "0 0 * * *"
+  # on demand
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  auto-update:
+    permissions:
+      # Needed for peter-evans/create-pull-request to create branch
+      contents: write
+      # Needed for peter-evans/create-pull-request to create a PR
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+
+      - uses: actions/create-github-app-token@f2acddfb5195534d487896a656232b016a682f3c # v1.9.0
+        id: app-token
+        with:
+          app-id: ${{ vars.SLICER_APP_ID }}
+          private-key: ${{ secrets.SLICER_APP_PRIVATE_KEY }}
+
+      - uses: actions/setup-python@0a5c61591373683505ea898e09a3ea4f39ef2b9c # v5.0.0
+        with:
+          python-version: 3.12
+
+      - run: pip install pre-commit
+
+      - name: pre-commit autoupdate
+        run: |
+          # To ensure the output only contain lines like the following:
+          #  `Updating https://github.com/org/user ... updating v1.2.3 -> v1.2.4`
+          # without interleaved string like the following:
+          #  `[INFO] Initializing environment for https://github.com/org/user.`
+          # we perform the autoupdate twice. This ensures the second run can easily be parsed.
+          pre-commit autoupdate --config .pre-commit-config.yaml 2>&1
+          git checkout -- .pre-commit-config.yaml
+          pre-commit autoupdate | tee /tmp/pre-commit-autoupdate.log
+
+      - name: Parse autoupdate output
+        id: parse-autoupdate
+        run: |
+          {
+            echo 'AUTOUPATE_LOG<<EOF'
+            echo "updates:"
+            while IFS= read -r line; do
+                repo_url=$(echo "$line" | sed -n 's/Updating \(https:\/\/github.com\/[^\/]\+\/[^\/]\+\) \.\.\. updating \(v[0-9.]\+\) -> \(v[0-9.]\+\)\./\1/p')
+                old_version=$(echo "$line" | sed -n 's/Updating \(https:\/\/github.com\/[^\/]\+\/[^\/]\+\) \.\.\. updating \(v[0-9.]\+\) -> \(v[0-9.]\+\)\./\2/p')
+                new_version=$(echo "$line" | sed -n 's/Updating \(https:\/\/github.com\/[^\/]\+\/[^\/]\+\) \.\.\. updating \(v[0-9.]\+\) -> \(v[0-9.]\+\)\./\3/p')
+
+                if [ -n "$repo_url" ] && [ -n "$old_version" ] && [ -n "$new_version" ]; then
+                    repo_name=$(echo "$repo_url" | awk -F'/' '{print $NF}')
+                    echo "- [${repo_url}: ${old_version} -> ${new_version}](pre-commit/${repo_name}@${old_version}...${new_version})"
+                fi
+            done < /tmp/pre-commit-autoupdate.log
+            echo EOF
+          } >> "$GITHUB_OUTPUT"
+
+      - run: pre-commit run --all-files
+
+      - uses: peter-evans/create-pull-request@a4f52f8033a6168103c2538976c07b467e8163bc # v6.0.1
+        with:
+          token: ${{ steps.app-token.outputs.token }}
+          commit-message: |
+            ENH: Update pre-commit hooks
+
+            steps.parse-autoupdate.outputs.AUTOUPATE_LOG
+          signoff: false
+          branch: update/pre-commit-hooks
+          delete-branch: true
+          title: "ENH: Update pre-commit hooks"
+          body: |
+            <!--pre-commit autoupdate log start-->
+            ${{ steps.parse-autoupdate.outputs.AUTOUPATE_LOG }}
+            <!--pre-commit autoupdate log start-->
+
+            This pull-request was auto-generated by the [pre-commit-autoupdate][1] GitHub action workflow.
+
+            [1]: https://github.com/${{ github.repository }}/blob/${{ steps.head_branch.outputs.sha }}/.github/workflows/pre-commit-autoupdate.yml
+          draft: false