Download visionOS SDK when building core

Author: tgoyne

.github/workflows/build-binaries.yml

@@ -19,6 +19,9 @@ jobs:
         target: [macosx, iphoneos, iphonesimulator, appletvos, appletvsimulator, watchos, watchsimulator, maccatalyst, xros, xrsimulator]
     steps:
       - uses: actions/checkout@v4
+      - name: Download visionOS
+        if: matrix.target == 'xros' || matrix.target == 'xrsimulator'
+        run: xcodebuild -downloadPlatform visionOS
 
       - name: Get Core Version
         id: get-core-version