cd fix (#24)

Author: psuzn

.github/workflows/deployment.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Exit if not on main branch
-        if: endsWith(github.ref, 'main') == false
+        if: github.ref != 'refs/heads/main'
         run: exit -1
 
       - uses: actions/checkout@v3