gradle: hello_xr: Migrate compileSdkVersion to compileSdk

Signed-off-by: utzcoz <[email protected]>

Author: utzcoz

src/tests/hello_xr/build.gradle

@@ -26,15 +26,15 @@ project.ext.repoRoot = file('../../../')
 apply from: file('../../version.gradle')
 
 android {
-    compileSdkVersion 29
+    compileSdk 29
     buildToolsVersion "30.0.3"
     ndkVersion "21.4.7075529"
 
     defaultConfig {
         applicationId "org.khronos.openxr.hello_xr"
         // for Vulkan, need at least 24
         minSdkVersion 24
-        compileSdkVersion 26
+        compileSdk 26
 
         versionName = project.versionOpenXR.toString() + project.versionQualifier
         versionCode = project.versionOpenXR.getVersionCode()