chore(ci): add maintenance label to dependabot PRs

Author: Anheledir

.github/dependabot.yml

@@ -6,18 +6,21 @@ updates:
   schedule:
     interval: "daily"
   open-pull-requests-limit: 25
-  labels: [ ]
+  labels:
+    - "maintenance"
 
 - package-ecosystem: nuget
   directory: "/"
   schedule:
     interval: "daily"
   open-pull-requests-limit: 25
-  labels: [ ]
+  labels:
+    - "maintenance"
 
 - package-ecosystem: "docker"
   directory: "/"
   schedule:
     interval: "daily"
   open-pull-requests-limit: 25
-  labels: [ ]
+  labels:
+    - "maintenance"