add version to androidx.compose.ui:ui-test-junit4

otherwise this will cause:

Execution failed for task ':app:generateGplayDebugAndroidTestLintModel'.
> Could not resolve all files for configuration ':app:gplayDebugAndroidTestRuntimeClasspath'.
   > Could not find androidx.compose.ui:ui-test-junit4:.
     Required by:
         project :app

Signed-off-by: Marcel Hibbe <dev@mhibbe.de>

app/build.gradle

@@ -298,7 +298,7 @@ dependencies {
     debugImplementation("androidx.compose.ui:ui-tooling")
 
     //tests
-    androidTestImplementation("androidx.compose.ui:ui-test-junit4")
+    androidTestImplementation("androidx.compose.ui:ui-test-junit4:1.6.8")
     debugImplementation("androidx.compose.ui:ui-test-manifest")
 
     testImplementation 'junit:junit:4.13.2'