use renovate instead of dependabot

.github/dependabot.yml

@@ -1,24 +0,0 @@
-version: 2
-updates:
-  - package-ecosystem: "maven"
-    directory: "/"
-    schedule:
-      interval: "weekly"
-    open-pull-requests-limit: 50
-  - package-ecosystem: "npm"
-    directory: "/commafeed-client"
-    schedule:
-      interval: "monthly"
-    open-pull-requests-limit: 50
-    groups:
-      mantine:
-        patterns:
-          - "@mantine/*"
-      lingui:
-        patterns:
-          - "@lingui/*"
-  - package-ecosystem: "github-actions"
-    directory: "/"
-    schedule:
-      interval: "weekly"
-    open-pull-requests-limit: 10