Only run CI for bors and pull requests

Author: Amanieu

.github/workflows/rust.yml

@@ -2,11 +2,11 @@ name: Rust
 
 on:
   push:
-    branches-ignore:
-      - trying.tmp
-      - staging.tmp
+    branches:
+      - trying
+      - staging
   pull_request:
-    
+
 env:
   RUST_TEST_THREADS: 1