[Vertex AI] Add CI for visionOS (#13092)

Author: andrewheard

.github/workflows/vertexai.yml

@@ -18,7 +18,7 @@ jobs:
   spm-unit:
     strategy:
       matrix:
-        target: [iOS, macOS, catalyst, tvOS]
+        target: [iOS, macOS, catalyst, tvOS, visionOS]
         os: [macos-14]
         include:
           - os: macos-14

FirebaseVertexAI/Tests/Unit/PartsRepresentableTests.swift

@@ -18,7 +18,7 @@ import FirebaseVertexAI
 import XCTest
 #if canImport(UIKit)
   import UIKit
-#else
+#elseif canImport(AppKit)
   import AppKit
 #endif
 
@@ -73,7 +73,7 @@ final class PartsRepresentableTests: XCTestCase {
     XCTFail("Expected model content from invlaid image to error")
   }
 
-  #if canImport(UIKit)
+  #if canImport(UIKit) && !os(visionOS) // These tests are stalling in CI on visionOS.
     func testModelContentFromInvalidUIImageThrows() throws {
       let image = UIImage()
       do {
@@ -103,7 +103,8 @@ final class PartsRepresentableTests: XCTestCase {
       let modelContent = try image.tryPartsValue()
       XCTAssert(modelContent.count > 0, "Expected non-empty model content for UIImage: \(image)")
     }
-  #else
+
+  #elseif canImport(AppKit)
     func testModelContentFromNSImageIsNotEmpty() throws {
       let coreImage = CIImage(color: CIColor.red)
         .cropped(to: CGRect(origin: CGPointZero, size: CGSize(width: 16, height: 16)))