build: configure Dependabot (#231)

Configure Dependabot

Author: yeikel

.github/dependabot.yml

@@ -0,0 +1,17 @@
+version: 2
+updates:
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "quarterly"
+    groups:
+      npm-packages:
+        patterns: [ "*" ]
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "quarterly"
+    groups:
+      github-action-workflows:
+        patterns: [ "*" ]