prepare release

Author: wuan

app/build.gradle

@@ -11,8 +11,8 @@ android {
         applicationId "org.blitzortung.android.app"
         minSdkVersion 15
         targetSdkVersion 29
-        versionCode 270
-        versionName '2.1.1'
+        versionCode 271
+        versionName '2.1.2'
         multiDexEnabled false
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }