Add missing annotations dependency

Issue: #5926
PiperOrigin-RevId: 249404152

extensions/ima/build.gradle

@@ -34,6 +34,7 @@ android {
 dependencies {
     api 'com.google.ads.interactivemedia.v3:interactivemedia:3.11.2'
     implementation project(modulePrefix + 'library-core')
+    implementation 'androidx.annotation:annotation:1.0.2'
     implementation 'com.google.android.gms:play-services-ads-identifier:16.0.0'
     testImplementation project(modulePrefix + 'testutils-robolectric')
 }