Increased default target sdk to 29 (#848)

* (android) increased default target sdk to 29

* Updated travis and appveyor to use build tools/api level 29

* Fixed two other files that was missing the API 29 update

spec/fixtures/android_studio_project/app/build.gradle

@@ -1,13 +1,13 @@
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 28
-    buildToolsVersion "28.0.3"
+    compileSdkVersion 29
+    buildToolsVersion "29.0.2"
 
     defaultConfig {
         applicationId "com.example.anis.myapplication"
         minSdkVersion 21
-        targetSdkVersion 28
+        targetSdkVersion 29
         versionCode 1
         versionName "1.0"
     }