switch CI to xcode 15

Author: NullIsOne

.github/workflows/Build.yml

@@ -7,6 +7,9 @@ on:
       - preview/version-8
   pull_request:
 
+env:
+  DEVELOPER_DIR: /Applications/Xcode_15.0.app/Contents/Developer
+
 jobs:
 
   build_iOS:
@@ -57,6 +60,9 @@ jobs:
   build_tvOS:
     runs-on: macOS-13
     steps:
+    - uses: maxim-lobanov/setup-xcode@v1
+      with:
+        xcode-version: '15.0.0'
     - uses: actions/checkout@v1
     - name: Generate projects
       run: make init

.github/workflows/Lint.yml

@@ -2,6 +2,9 @@ name: Lint
 
 on: [pull_request]
 
+env:
+  DEVELOPER_DIR: /Applications/Xcode_15.0.app/Contents/Developer
+
 jobs:
   danger:
     runs-on: ubuntu-latest