Require mozrunner 6.5

https://bugzilla.mozilla.org/show_bug.cgi?id=1105837
Add support for win64 inbound

https://bugzilla.mozilla.org/show_bug.cgi?id=1105856
Merge pull request #138 from vaibhavmagarwal/mozregression-inbound64

Add support for win64 inbound
Bump version to 0.28

(skipped version 0.27, which I forgot to commit)