[chore]: try bumping Xcode version to fix build failures

Author: jamieQ

.github/workflows/swift.yaml

@@ -7,13 +7,15 @@ on:
   pull_request:
 
 env:
-  XCODE_VERSION: 16.1.0
+  XCODE_VERSION: 16.3.0
+  # FIXME: revert to macos-latest when Xcode 16.3 is available by end of August 2025
+  MACOS_LABEL: macos-15
   TUIST_TEST_DEVICE: iPad (10th generation)
   TUIST_TEST_PLATFORM: iOS
 
 jobs:
   development-tests:
-    runs-on: macos-latest
+    runs-on: ${{ env.MACOS_LABEL }}
 
     name: "development-tests [iOS ${{ matrix.sdk }}]"
 
@@ -62,7 +64,7 @@ jobs:
 
   # FIXME: these should probably be run with a matrix too
   snapshot-tests:
-    runs-on: macos-latest
+    runs-on: ${{ env.MACOS_LABEL }}
 
     env:
       TUIST_TEST_OS: 18.1
@@ -85,7 +87,7 @@ jobs:
       run: tuist test --path Samples
 
   package-tests:
-    runs-on: macos-latest
+    runs-on: ${{ env.MACOS_LABEL }}
 
     steps:
     - uses: actions/checkout@v4
@@ -99,7 +101,7 @@ jobs:
       run: swift test
 
   tutorial:
-    runs-on: macos-latest
+    runs-on: ${{ env.MACOS_LABEL }}
 
     steps:
     - uses: actions/checkout@v4
@@ -115,7 +117,7 @@ jobs:
       run: tuist test --path Samples/Tutorial TutorialTests
 
   swiftformat:
-    runs-on: macos-latest
+    runs-on: ${{ env.MACOS_LABEL }}
 
     steps:
     - uses: actions/checkout@v4