Configure Dependabot for GitHub Actions and Gradle (#53)

* Configure Dependabot for GitHub Actions and Gradle

Added support for GitHub Actions and Gradle updates.

* Add groups for CI actions and lib dependencies

Author: rfc2822

.github/dependabot.yml

@@ -0,0 +1,29 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  # Github Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    commit-message:
+      prefix: "[CI] "
+    groups:
+      ci-actions:
+        patterns: ["*"]
+      
+  # Gradle
+  - package-ecosystem: "gradle"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    groups:
+      lib-dependencies:
+        patterns: ["*"]
+    ignore:
+      - dependency-name: "ical4j"
+        versions: ["4.x"]