Added dependabot and auto-merge for it

.github/dependabot.yml

@@ -0,0 +1,25 @@
+{
+  "version": 2,
+  "updates": [
+    {
+      "allow": [
+        {
+          "dependency-type": "all"
+        }
+      ],
+      "directory": "/",
+      "package-ecosystem": "composer",
+      "schedule": {
+        "interval": "daily"
+      },
+      "versioning-strategy": "increase"
+    },
+    {
+      "directory": "/",
+      "package-ecosystem": "github-actions",
+      "schedule": {
+        "interval": "daily"
+      }
+    }
+  ]
+}

.github/workflows/merge-dependabot-upgrades.yml

@@ -0,0 +1,23 @@
+# See https://github.com/ridedott/merge-me-action/
+# This workflow automates merges from patches sent by Dependabot, and
+# only by dependabot, once the other CI workflows pass
+name: Auto-merge Dependabot PRs
+
+on:
+  workflow_run:
+    types:
+      - completed
+    workflows:
+      - "Continuous Integration"
+
+jobs:
+  merge-me:
+    name: Auto-merge Dependabot PRs
+    runs-on: ubuntu-latest
+    steps:
+      - name: Auto-Merge
+        if: ${{ github.event.workflow_run.conclusion == 'success' }}
+        uses: ridedott/merge-me-action@v2.9.35
+        with:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          MERGE_METHOD: MERGE