remove bors and use merge_group

Author: Emilgardis

.github/bors.toml

@@ -1,7 +1,8 @@
 on:
   push:
-    branches: [ staging, trying, master ]
+    branches: master
   pull_request:
+  merge_group:
 
 name: Continuous Integration
 

.github/workflows/ci.yml

@@ -1,7 +1,8 @@
 on:
   push:
-    branches: [ staging, trying, master ]
+    branches: master
   pull_request:
+  merge_group:
 
 name: Code formatting check