Bump mockwebserver from 4.2.2 to 4.3.1

Bumps [mockwebserver](https://github.com/square/okhttp) from 4.2.2 to 4.3.1.
- [Release notes](https://github.com/square/okhttp/releases)
- [Changelog](https://github.com/square/okhttp/blob/master/CHANGELOG.md)
- [Commits](square/okhttp@parent-4.2.2...parent-4.3.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

build.gradle

@@ -61,7 +61,7 @@ dependencies {
   testCompile group: 'org.hamcrest', name: 'hamcrest-library', version: '2.2'
   testCompile group: 'org.skyscreamer', name: 'jsonassert', version: '1.5.0'
   testCompile group: 'org.jsoup', name: 'jsoup', version: '1.12.1'
-  testCompile 'com.squareup.okhttp3:mockwebserver:4.2.2'
+  testCompile 'com.squareup.okhttp3:mockwebserver:4.3.1'
 }
 
 sourceSets {