update build tools

app/build.gradle

@@ -11,7 +11,7 @@ apply plugin: 'com.google.protobuf'
 
 android {
     compileSdkVersion 29
-    buildToolsVersion "29.0.2"
+    buildToolsVersion "29.0.3"
     defaultConfig {
         applicationId "com.geeksville.mesh"
         minSdkVersion 22 // The oldest emulator image I have tried is 22 (though 21 probably works)