github: add dependabot configuration

Author: rpkelly

.github/dependabot.yaml

@@ -0,0 +1,17 @@
+version: 2
+updates:
+
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    labels:
+      - "area/dependencies"
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    labels:
+      - "area/dependencies"
+    open-pull-requests-limit: 0