chore: update dependabot schedule and pull request limit

- Change dependency update interval from weekly to monthly
- Increase open pull requests limit from 10 to 50

This change aims to reduce the frequency of dependency update checks and manage the number of open pull requests more effectively.

.github/dependabot.yml

@@ -7,29 +7,29 @@ updates:
   - package-ecosystem: "pip"
     directory: "/"
     schedule:
-      interval: "weekly"
+      interval: "monthly"
     allow:
       - dependency-type: "all"
     commit-message:
       prefix: ":arrow_up:"
-    open-pull-requests-limit: 10
+    open-pull-requests-limit: 50
 
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
-      interval: "weekly"
+      interval: "monthly"
     allow:
       - dependency-type: "all"
     commit-message:
       prefix: ":arrow_up:"
-    open-pull-requests-limit: 10
+    open-pull-requests-limit: 50
 
   - package-ecosystem: "docker"
     directory: "/docker"
     schedule:
-      interval: "weekly"
+      interval: "monthly"
     allow:
       - dependency-type: "all"
     commit-message:
       prefix: ":arrow_up:"
-    open-pull-requests-limit: 10
+    open-pull-requests-limit: 50