[gradle]: Bump androidx.annotation:annotation

Bumps androidx.annotation:annotation from 1.7.0 to 1.9.1.

---
updated-dependencies:
- dependency-name: androidx.annotation:annotation
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

packages/google_maps_flutter/google_maps_flutter_android/android/build.gradle

@@ -36,7 +36,7 @@ android {
     }
 
     dependencies {
-        implementation "androidx.annotation:annotation:1.7.0"
+        implementation "androidx.annotation:annotation:1.9.1"
         implementation 'com.google.android.gms:play-services-maps:18.2.0'
         implementation 'com.google.maps.android:android-maps-utils:3.6.0'
         androidTestImplementation 'androidx.test:runner:1.2.0'