Fix the dependabot setup

Author: christophfroehlich

.github/dependabot.yml

@@ -11,17 +11,3 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
-  - package-ecosystem: "github-actions"
-    # Workflow files stored in the
-    # default location of `.github/workflows`
-    directory: "/"
-    schedule:
-      interval: "weekly"
-    target-branch: "jazzy"
-  - package-ecosystem: "github-actions"
-    # Workflow files stored in the
-    # default location of `.github/workflows`
-    directory: "/"
-    schedule:
-      interval: "weekly"
-    target-branch: "humble"