app: Regularly scheduled gradle updates

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/build.gradle

@@ -5,7 +5,7 @@ apply plugin: 'com.android.application'
 final def keystorePropertiesFile = rootProject.file("keystore.properties")
 
 android {
-    buildToolsVersion '27.0.3'
+    buildToolsVersion '28.0.0'
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_8
         targetCompatibility JavaVersion.VERSION_1_8
@@ -49,8 +49,9 @@ android {
         }
     }
 }
+
 ext {
-    databindingVersion = '3.1.2'
+    databindingVersion = '3.1.3'
     supportLibsVersion = '27.1.1'
     streamsupportVersion = '1.6.0'
 }