add dependabot configuration

Author: thestinger

.github/dependabot.yml

@@ -0,0 +1,14 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: daily
+    target-branch: main
+    open-pull-requests-limit: 20
+  - package-ecosystem: gradle
+    directory: "/"
+    schedule:
+      interval: daily
+    target-branch: main
+    open-pull-requests-limit: 20