Update build tools

Signed-off-by: Mario Danic <mario@lovelyhq.com>

app/build.gradle

@@ -4,7 +4,7 @@ apply plugin: 'kotlin-android'
 
 android {
     compileSdkVersion 27
-    buildToolsVersion '27.0.2'
+    buildToolsVersion '27.0.3'
     defaultConfig {
         applicationId "com.nextcloud.talk2"
         versionName version