updated mock server docker file for the latest gradle distribution format
updated mock server docker file for the latest gradle distribution format

olga-vasylchenko/pact-jvm,algra/pact-jvm,DiUS/pact-jvm,DiUS/pact-jvm,algra/pact-jvm,Fitzoh/pact-jvm,flaregames/pact-jvm,Fitzoh/pact-jvm