Enable dependabot.

Author: joehni

.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:
+  - package-ecosystem: "maven" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "monthly"
+    groups:
+      plugins:
+        patterns:
+          - "*:*-plugins:*"
+    ignore:
+      - dependency-name: "org.apache.maven.plugins:*"
+        versions: ["[4.x,)"] # These are for Maven 4
+      - dependency-name: "*"
+        update-types: ["version-update:semver-major"] # No MRs for major versions
+    open-pull-requests-limit: 100
+  - package-ecosystem: "github-actions" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "monthly"
+    groups:
+      github-actions:
+        patterns:
+          - "*"