Fix checks running twice on pull requests

Author: zanieb

.github/workflows/check.yml

@@ -1,7 +1,8 @@
-name: Check
+name: check
 
 on:
   push:
+    branches: [main]
   pull_request:
 
 concurrency:

.github/workflows/linux.yml

@@ -58,6 +58,7 @@ jobs:
           - gcc
           - xcb
           - xcb.cross
+    name: ${{ matrix.image }}
     runs-on: depot-ubuntu-22.04
     permissions:
       packages: write