ci: add GitHub Actions workflow to automatically update Packagist on push and tags

Author: wardvisual

.github/workflows/packagist-update.yml

@@ -0,0 +1,19 @@
+
+```yaml
+name: Update Packagist
+
+on:
+  push:
+    branches: [ main, master ]
+    tags: [ 'v*' ]
+
+jobs:
+  update-packagist:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Update Packagist
+        run: |
+          curl -XPOST -H "content-type:application/json" \
+          "https://packagist.org/api/update-package?username=wardvisual&apiToken=${{ secrets.PACKAGIST_API_TOKEN }}" \
+          -d '{"repository":{"url":"https://github.com/wardvisual/warvilphp"}}'