chore: automatically update available PostgreSQL versions (#269)

Automatically update PostgreSQL versions in the Bake file; this will retrieve
the information from the official PostgreSQL website.

Closes #153

Signed-off-by: Jonathan Gonzalez V <jonathan.gonzalez@enterprisedb.com>
Signed-off-by: Niccolò Fei <niccolo.fei@enterprisedb.com>
Co-authored-by: Niccolò Fei <niccolo.fei@enterprisedb.com>

.github/workflows/bake_update.yml

@@ -0,0 +1,67 @@
+name: Update PostgreSQL versions
+
+on:
+  schedule:
+    - cron: 0 0 * * 1
+  workflow_dispatch:
+
+defaults:
+  run:
+    shell: 'bash -Eeuo pipefail -x {0}'
+
+permissions: read-all
+
+jobs:
+  build:
+    name: Run update script
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+        with:
+          token: ${{ secrets.REPO_GHA_PAT }}
+
+      - name: Run update script
+        uses: nick-fields/retry@ce71cc2ab81d554ebbe88c79ab5975992d79ba08 # v3
+        with:
+          timeout_minutes: 15
+          max_attempts: 3
+          command: |
+            VERSIONS="$(
+            curl -Ss -q https://www.postgresql.org/versions.json \
+            | jq -r '[.[] | select(.supported == true) | .major + "." + .latestMinor]
+            | sort
+            | map("  \"" + . + "\"")
+            | join(",\n")' \
+            | sed '1i postgreSQLVersions = [' \
+            | sed '$a ]'
+            )"
+            printf '%s\n' "$VERSIONS" \
+            | sed -i '/^postgreSQLVersions = \[/,/^]/d;/^\/\/ PostgreSQL versions/r /dev/stdin' docker-bake.hcl
+
+      - name: Diff
+        run: |
+          git status
+          git diff
+
+      - name: Temporarily disable "include administrators" branch protection
+        if: ${{ always() && github.ref == 'refs/heads/main' }}
+        id: disable_include_admins
+        uses: benjefferies/branch-protection-bot@af281f37de86139d1c7a27b91176b5dc1c2c827c # v1.1.2
+        with:
+          access_token: ${{ secrets.REPO_GHA_PAT }}
+          branch: main
+          enforce_admins: false
+
+      - uses: EndBug/add-and-commit@a94899bca583c204427a224a7af87c02f9b325d5 # v9
+        with:
+          author_name: CloudNativePG Automated Updates
+          author_email: noreply@cnpg.com
+          message: 'chore: update PostgreSQL versions'
+
+      - name: Enable "include administrators" branch protection
+        uses: benjefferies/branch-protection-bot@af281f37de86139d1c7a27b91176b5dc1c2c827c # v1.1.2
+        if: ${{ always() && github.ref == 'refs/heads/main' }}
+        with:
+          access_token: ${{ secrets.REPO_GHA_PAT }}
+          branch: main
+          enforce_admins: ${{ steps.disable_include_admins.outputs.initial_status }}