bump build tools to 26.0.3 (#19831)

Summary:
This will bump android build tools to 26.0.3, and will remove warning about newer version of build tools in Android Studio, thus improve developer experience.
Closes https://github.com/facebook/react-native/pull/19831

Differential Revision: D8620094

Pulled By: hramos

fbshipit-source-id: fa1c6739bb7556736c1b323acea88fe87e82f4d7

RNTester/android/app/build.gradle

@@ -85,7 +85,7 @@ def enableProguardInReleaseBuilds = false
 
 android {
     compileSdkVersion 26
-    buildToolsVersion "26.0.2"
+    buildToolsVersion "26.0.3"
 
     defaultConfig {
         applicationId "com.facebook.react.uiapp"

ReactAndroid/build.gradle

@@ -246,7 +246,7 @@ task packageReactNdkLibsForBuck(dependsOn: packageReactNdkLibs, type: Copy) {
 
 android {
     compileSdkVersion 26
-    buildToolsVersion "26.0.2"
+    buildToolsVersion "26.0.3"
 
     defaultConfig {
         minSdkVersion 16

local-cli/templates/HelloWorld/android/app/build.gradle

@@ -95,7 +95,7 @@ def enableProguardInReleaseBuilds = false
 
 android {
     compileSdkVersion 26
-    buildToolsVersion "26.0.2"
+    buildToolsVersion "26.0.3"
 
     defaultConfig {
         applicationId "com.helloworld"

scripts/.tests.env

@@ -4,7 +4,7 @@
 
 ## ANDROID ##
 # Android SDK Build Tools revision
-export ANDROID_SDK_BUILD_TOOLS_REVISION=26.0.2
+export ANDROID_SDK_BUILD_TOOLS_REVISION=26.0.3
 # Android API Level we build with
 export ANDROID_SDK_BUILD_API_LEVEL="26"
 # Google APIs for Android level