Set Xcode 15.1 on GitHub Action

Author: backslash-f

.github/workflows/swift.yml

@@ -1,15 +1,12 @@
 ---
-name: "ci"
-
-on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
+name: "CI"
+on: [push]
 
 jobs:
   test:
     runs-on: macOS-latest
+    env:
+      DEVELOPER_DIR: /Applications/Xcode_15.1.app/Contents/Developer
     steps:
       - uses: actions/checkout@v4
       - name: Run Tests