Update branch for CI from master to main (#819)

This was missed when we switched to using `main`.

Author: sds

.github/workflows/lint.yml

@@ -1,9 +1,9 @@
 name: Lint
 on:
   push:
-    branches: [master]
+    branches: [main]
   pull_request:
-    branches: [master]
+    branches: [main]
 
 jobs:
   overcommit:
@@ -16,7 +16,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 2.7
+          ruby-version: 3.3
           bundler-cache: true
 
       - name: Prepare environment

.github/workflows/tests.yml

@@ -1,9 +1,9 @@
 name: Tests
 on:
   push:
-    branches: [master]
+    branches: [main]
   pull_request:
-    branches: [master]
+    branches: [main]
 
 jobs:
   rspec: