Downgrade to okhttp3 3.14.2

The upgrade to 4.x was breaking some behavior in our tests.
We need to reconsider this upgrade and check our mockrestserver usage in
our tests.

Author: bclozel

build.gradle

@@ -149,7 +149,7 @@ configure(allprojects) { project ->
 				}
 			}
 
-			dependencySet(group: 'com.squareup.okhttp3', version: '4.1.0') {
+			dependencySet(group: 'com.squareup.okhttp3', version: '3.14.2') {
 				entry 'okhttp'
 				entry 'mockwebserver'
 			}