Fix parsing of rpmbuild output

[Zlopez]

Previously rpmbuild output didn't take into consideration errors or warnings. Let's parse it more smartly.

Fixes #565

[softwarefactory-project-zuul[bot]]

Build failed. More information on how to proceed and troubleshoot errors available at https://fedoraproject.org/wiki/Zuul-based-ci https://fedora.softwarefactory-project.io/zuul/buildset/d908fd0bb4ad4f4788f921026aae477d

:x: fi-tox-mypy FAILURE in 10m 53s :x: fi-tox-lint FAILURE in 10m 38s :x: fi-tox-format FAILURE in 11m 03s :x: fi-tox-python38 FAILURE in 11m 23s :heavy_check_mark: fi-tox-python39 SUCCESS in 11m 44s :x: fi-tox-python310 FAILURE in 11m 25s :x: fi-tox-docs FAILURE in 11m 21s :x: fi-tox-bandit FAILURE in 11m 10s :x: fi-tox-diff-cover FAILURE in 12m 19s

[softwarefactory-project-zuul[bot]]

Build failed. More information on how to proceed and troubleshoot errors available at https://fedoraproject.org/wiki/Zuul-based-ci https://fedora.softwarefactory-project.io/zuul/buildset/3313211761de4946be57f9cd7b70d219

:x: fi-tox-mypy FAILURE in 15m 22s :heavy_check_mark: fi-tox-lint SUCCESS in 15m 40s :heavy_check_mark: fi-tox-format SUCCESS in 15m 17s :x: fi-tox-python38 FAILURE in 15m 53s :x: fi-tox-python39 FAILURE in 15m 37s :x: fi-tox-python310 FAILURE in 15m 27s :x: fi-tox-docs FAILURE in 15m 06s :x: fi-tox-bandit FAILURE in 15m 05s :x: fi-tox-diff-cover FAILURE in 16m 11s

[softwarefactory-project-zuul[bot]]

Build succeeded. https://fedora.softwarefactory-project.io/zuul/buildset/cd8f5b37540e4c24a5db16885e766590

:heavy_check_mark: fi-tox-mypy SUCCESS in 9m 45s :heavy_check_mark: fi-tox-lint SUCCESS in 9m 45s :heavy_check_mark: fi-tox-format SUCCESS in 9m 28s :heavy_check_mark: fi-tox-python38 SUCCESS in 10m 13s :heavy_check_mark: fi-tox-python39 SUCCESS in 10m 08s :heavy_check_mark: fi-tox-python310 SUCCESS in 10m 00s :heavy_check_mark: fi-tox-docs SUCCESS in 9m 57s :heavy_check_mark: fi-tox-bandit SUCCESS in 9m 40s :heavy_check_mark: fi-tox-diff-cover SUCCESS in 11m 10s