chore: bump OkHttp client version

Versions above 3.12.x have dropped support for Java 7.

Related: https://square.github.io/okhttp/changelog_3x/#version-3130

Author: darrachequesne

pom.xml

@@ -49,7 +49,7 @@
     <dependency>
       <groupId>com.squareup.okhttp3</groupId>
       <artifactId>okhttp</artifactId>
-      <version>3.8.1</version>
+      <version>3.12.12</version>
     </dependency>
     <dependency>
       <groupId>org.json</groupId>