Add Dependabot (#2538)

* Create .dependabot

* Rename .dependabot to dependabot.yml

.github/dependabot.yml

@@ -0,0 +1,25 @@
+# Configuration options:
+# https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#about-the-dependabotyml-file
+
+version: 2
+
+updates:
+    - package-ecosystem: "gradle"
+      directory: "/"
+      schedule:
+        interval: "weekly"
+      registries:
+        - maven-google
+
+    - package-ecosystem: "github-actions"
+      directory: "/"
+      schedule:
+        interval: "weekly"
+
+# This is only a workaround as long as
+# https://github.com/dependabot/dependabot-core/pull/7260
+# is not merged
+registries:
+  maven-google:
+    type: maven-repository
+    url: "https://dl.google.com/dl/android/maven2/"