[TASK] Set the target milestone for the Dependabot updates (#713)

Author: oliverklee

.github/dependabot.yml

@@ -6,6 +6,7 @@ updates:
       directory: "/"
       schedule:
           interval: "daily"
+      milestone: 1
 
     - package-ecosystem: "composer"
       directory: "/"
@@ -14,3 +15,4 @@ updates:
       allow:
           - dependency-type: "development"
       versioning-strategy: "increase"
+      milestone: 1