Update Travis CI config

Author: mannodermaus

.travis.yml

@@ -11,7 +11,7 @@ android:
   components:
   - tools
   - platform-tools
-  - build-tools-26.0.1
+  - build-tools-26.0.2
   - android-26
 
 jdk:

README.md

@@ -66,7 +66,7 @@ To work around this, there is a separate dependency you can add to the *test* sc
 of your project in Android Studio 3. It provides its own copy of the JUnit 5 Runtime
 provided by a more recent build of IntelliJ, overriding the one embedded in Android Studio.
 
-To use this, add the following line alongside the other `junit5()` dependency:
+To use this, add the following line alongside the other `junit5()` dependencies:
 
 ```groovy
 testCompileOnly junit5EmbeddedRuntime()