GitHub: Improve Dependabot. (#12038)

Co-authored-by: Marco Ebert <[email protected]>

.github/dependabot.yml

@@ -1,7 +1,6 @@
----
 version: 2
 updates:
-  - package-ecosystem: "gomod"
+  - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
@@ -10,32 +9,35 @@ updates:
       - "release-note-none"
       - "ok-to-test"
     groups:
-      all:
+      actions:
         update-types:
+          - "minor"
           - "patch"
-  - package-ecosystem: "github-actions"
-    directory: "/"
+  - package-ecosystem: "docker"
+    directories:
+      - "**/rootfs"
     schedule:
       interval: "weekly"
     labels:
       - "area/dependency"
       - "release-note-none"
       - "ok-to-test"
     groups:
-      all:
+      docker:
         update-types:
           - "minor"
           - "patch"
-  - package-ecosystem: "docker"
-    directory: "/images"
+  - package-ecosystem: "gomod"
+    directories:
+      - "/"
+      - "**/rootfs"
     schedule:
       interval: "weekly"
     labels:
       - "area/dependency"
       - "release-note-none"
       - "ok-to-test"
     groups:
-      actions:
+      go:
         update-types:
-          - "minor"
           - "patch"