ci: add dependabot and automerge job to make deps always up to date

.github/dependabot.yml

@@ -0,0 +1,15 @@
+# Basic dependabot.yml file with
+# minimum configuration for two package managers
+
+version: 2
+updates:
+  # Enable version updates for npm
+  - package-ecosystem: 'npm'
+    directory: '/'
+    schedule:
+      interval: 'daily'
+    # Specify labels for npm pull requests
+    labels:
+      - 'npm'
+      - 'dependencies'
+    versioning-strategy: increase

.github/workflows/yarn.js.yml

@@ -24,3 +24,14 @@ jobs:
         run: yarn lint
       - name: Test
         run: yarn test
+
+  dependabot:
+    needs:
+      - Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: auto-merge
+        uses: ridedott/dependabot-auto-merge-action@master
+        with:
+          GITHUB_LOGIN: dependabot[bot]
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}