Reflect the move from master to main

Author: domenic

.github/workflows/build.yml

@@ -1,11 +1,9 @@
 name: Build
 on:
   pull_request:
-    branches:
-    - master
+    branches: [main]
   push:
-    branches:
-    - master
+    branches: [main]
 jobs:
   build:
     name: Lint and tests