ci(renovate): initial commit of basic Renovate config

*  Enable only the `gitlab-ci` manager for now.
   `automergeStrategy: 'merge-commit'` as Renovate defaults to `squash`
   which conflicts with `semantic-release` (commit messages are lost).
   Schedule to generate PRs only on Tuesdays to prevent a noisy
   repository. Custom Docker images are published on Mondays.
*  Remove Renovate config from converted formulas as this specific
   config is tailored for the `template-formula`.

Author: dafyddj

.github/renovate.json5

@@ -0,0 +1,14 @@
+{
+  $schema: 'https://docs.renovatebot.com/renovate-schema.json',
+  enabledManagers: [
+    'gitlabci',
+  ],
+  extends: [
+    'config:best-practices',
+  ],
+  automergeStrategy: 'merge-commit',
+  dependencyDashboardTitle: 'Renovate Dashboard',
+  schedule: [
+    '* * * * 2',        // Tuesdays only
+  ],
+}

.pre-commit-config.yaml

@@ -93,3 +93,8 @@ repos:
                 docs/index.rst|
             )$
         additional_dependencies: [pygments==2.16.1]
+  - repo: https://github.com/renovatebot/pre-commit-hooks
+    rev: 40.5.0
+    hooks:
+      - id: renovate-config-validator
+        name: Check Renovate config with renovate-config-validator

bin/convert-formula.sh

@@ -56,7 +56,9 @@ convert_formula() {
     | git commit-tree 'HEAD^{tree}')"
   git rm --quiet bin/convert-formula.sh AUTHORS.md CHANGELOG.md \
     docs/_static/css/custom.css docs/AUTHORS.rst docs/CHANGELOG.rst \
-    docs/conf.py docs/CONTRIBUTING_DOCS.rst docs/index.rst
+    docs/conf.py docs/CONTRIBUTING_DOCS.rst docs/index.rst \
+    .github/renovate.json5 \
+    && :
   tag_out=$(git tag --list | xargs git tag --delete)
   if [ "${DEBUG:-false}" = "true" ]; then
     echo "$tag_out"