Update ubuntu.yml

Author: lemire

.github/workflows/ubuntu.yml

@@ -1,12 +1,6 @@
 name: Ubuntu 22.04 Sanitized CI (GCC 11)
 
-on:
-  push:
-    branches:
-      - master
-  pull_request:
-    branches:
-      - master
+on: [push, pull_request]
 
 jobs:
   ubuntu-build:
@@ -23,4 +17,4 @@ jobs:
           mkdir build &&
           cd build &&
           cmake  ..   &&
-          cmake --build .
+          cmake --build .