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* Removed `xmler` dependency, simplified, and re-implemented the logic using `xmltodict`.
* Added more tests, including for the CLI and increased tests coverage over 96%.
* Added Python 3.8 to supported versions.
* Removed Python 3.4 from supported versions.
NOTE: This was supposed to be 0.1.4, but instead of `bumprevision patch` I ran
`bumprevision minor`, and since the PR is yet be pass TravisCI, I'll do a follow-up
patch release.