Update ci.yml to run CI on master branch PRs
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a5b7cf8..665a5bc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,7 +4,7 @@
 on: 
   pull_request:
     branches:
-        - main
+        - master
   push:
   workflow_dispatch: