build: update dependabot configuration for npm, docker, and github-actions (#59)

Author: mgaebler

.github/dependabot.yml

@@ -9,3 +9,19 @@ updates:
     directory: "/" # Location of package manifests
     schedule:
       interval: "weekly"
+    groups:
+      all-minor-patch-updates:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
+    open-pull-requests-limit: 20
+  - package-ecosystem: "docker" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "github-actions" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "monthly"