Add forgejo action

.forgejo/workflows/renovate.yaml

@@ -0,0 +1,25 @@
+on:
+  push:
+  schedule:
+    - cron: "* */4 * * *"
+
+jobs:
+  renovate:
+    runs-on: docker
+    container:
+      image: 'renovate/renovate:37.146.0'
+    steps:
+      - name: Validate config
+        # unset from https://github.com/renovatebot/renovate/discussions/15049
+        run: |
+          unset GIT_COMMITTER_NAME GIT_COMMITTER_EMAIL GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL
+          renovate-config-validator
+      - name: Renovate
+        run: |
+          unset GIT_COMMITTER_NAME GIT_COMMITTER_EMAIL GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL
+          renovate
+        env:
+          # ForgeJo token used to authenticate as the renovate user
+          RENOVATE_TOKEN: ${{ secrets.RENOVATE_TOKEN }}
+          # token used to avoid rate limits when checking for version
+          GITHUB_COM_TOKEN: ${{ secrets.PERSONAL_TOKEN_GITHUB }}