circleci: use `github-release` for managing releases

[sameersbn]

The ghr tools -delete argument deletes a release and its git tag in advance if it exists. The deletion of the tag is likely the reason the build loop is relaunched after the tag is recreated. Ideally -delete should only delete the github release and not perform any operations on the git repo.

In this PR I have replaced ghr with the github-release tool which is feature rich and does not delete tags when a release is deleted.

Closes triggermesh/tm#161

ref:

• https://github.com/tcnksm/ghr/blob/master/README.md#options