Frequent heap exceptions (out of memory)

[ishtiaque05]

This is strange but running all the tests from this branch (#76) is causing frequent heap exceptions. The problem might be with CodeShovel caching as some test takes forever to run, however, when restarted separately it works fine :/

Originally posted by @ishtiaque05 in https://github.com/ataraxie/codeshovel/issues/76#issuecomment-843699433