Restore the Dependabot open PR limit

This effectively reverts #90. Restoring the limit because of the useless amount of CI run this causes if Dependabot has several PR's open and it has to rebase due to another PR getting merged.

.github/dependabot.yml

@@ -1,11 +1,11 @@
 version: 2
 updates:
-    - package-ecosystem: "composer"
-      directory: "/"
-      schedule:
-          interval: "daily"
-          time: "05:00"
-      labels:
-          - "Dependencies 📦"
-          - "PHP 🐘"
-      versioning-strategy: "increase"
+  - package-ecosystem: "composer"
+    directory: "/"
+    schedule:
+      interval: "daily"
+      time: "03:00"
+    labels:
+      - "Dependabot 🤖"
+    versioning-strategy: "increase"
+    open-pull-requests-limit: 1