Add GitHub sync workflow (every 6h)

.forgejo/workflows/sync.yaml

@@ -0,0 +1,36 @@
+name: Sync from GitHub
+
+on:
+  schedule:
+    - cron: "0 */6 * * *"
+  workflow_dispatch:
+
+jobs:
+  sync:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone repo
+        run: |
+          git clone https://git.joshuahirsig.xyz/docker/pokemon-or-military.git .
+          git config user.name "forgejo-bot"
+          git config user.email "bot@joshuahirsig.xyz"
+
+      - name: Fetch upstream
+        run: |
+          git remote add upstream https://github.com/mathieuviart/PokemonTCGSetOrMilitaryOperation.git
+          git fetch upstream main
+
+      - name: Check for changes
+        id: check
+        run: |
+          if git merge-base --is-ancestor upstream/main HEAD; then
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Merge and push
+        if: steps.check.outputs.changed == 'true'
+        run: |
+          git merge upstream/main --no-edit
+          git push https://joshii:${{ secrets.REGISTRY_TOKEN }}@git.joshuahirsig.xyz/docker/pokemon-or-military.git HEAD:main