Add version collition error handling for Android publish (#14835)

examples/flutter_gallery/android/fastlane/Fastfile

@@ -9,6 +9,7 @@ default_platform(:android)
 platform :android do
   desc 'Push the built release APK to alpha or beta depending on current branch'
   lane :deploy_play_store do
+    begin
       upload_to_play_store(
         track: ENV['TRAVIS_BRANCH'] == 'beta' ? 'beta' : 'alpha',
         apk: '../build/app/outputs/apk/release/app-release.apk',
@@ -16,5 +17,9 @@ platform :android do
         skip_upload_screenshots: true,
         skip_upload_images: true
       )
+    rescue => exception
+      raise exception unless exception.message.include?('apkUpgradeVersionConflict')
+      puts 'Current version already present on the Play Store. Omitting this upload.'
+    end
   end
 end