Fix CI workflow condition syntax

Removed '|| ""' from the if condition which may have been preventing
the workflow from running properly.

Author: nickprotop

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     # Skip CI if commit message contains [skip ci]
-    if: ${{ !contains(github.event.head_commit.message || '', '[skip ci]') }}
+    if: ${{ !contains(github.event.head_commit.message, '[skip ci]') }}
 
     steps:
       - name: Checkout code