CI: Update macOS runner for building to use Xcode 16.4

The current version of swift-format uses features that are only
supported in more recent Swift compiler versions than the one shipped
with Xcode 16.1.0.

.github/workflows/analyze-project.yaml

@@ -57,8 +57,8 @@ jobs:
           : Set Up Environment 🔧
           if (( ${+RUNNER_DEBUG} )) setopt XTRACE
 
-          print '::group::Enable Xcode 16.1'
-          sudo xcode-select --switch /Applications/Xcode_16.1.0.app/Contents/Developer
+          print '::group::Enable Xcode 16.4'
+          sudo xcode-select --switch /Applications/Xcode_16.4.app/Contents/Developer
           print '::endgroup::'
 
           print '::group::Clean Homebrew Environment'

.github/workflows/build-project.yaml

@@ -80,8 +80,8 @@ jobs:
           : Set Up Environment 🔧
           if (( ${+RUNNER_DEBUG} )) setopt XTRACE
 
-          print '::group::Enable Xcode 16.1'
-          sudo xcode-select --switch /Applications/Xcode_16.1.0.app/Contents/Developer
+          print '::group::Enable Xcode 16.4'
+          sudo xcode-select --switch /Applications/Xcode_16.4.app/Contents/Developer
           print '::endgroup::'
 
           print '::group::Clean Homebrew Environment'