Add towncrier and tox to dev dependencies

[Zlopez]

Update documentation to reflect this change

[softwarefactory-project-zuul[bot]]

Build succeeded. https://fedora.softwarefactory-project.io/zuul/buildset/11b27013c5894e698641fac99c8d3351

:heavy_check_mark: fi-tox-mypy SUCCESS in 10m 02s :heavy_check_mark: fi-tox-lint SUCCESS in 10m 05s :heavy_check_mark: fi-tox-format SUCCESS in 9m 59s :heavy_check_mark: fi-tox-python38 SUCCESS in 11m 00s :heavy_check_mark: fi-tox-python39 SUCCESS in 10m 45s :heavy_check_mark: fi-tox-python310 SUCCESS in 10m 34s :heavy_check_mark: fi-tox-python311 SUCCESS in 10m 31s :heavy_check_mark: fi-tox-docs SUCCESS in 10m 24s :heavy_check_mark: fi-tox-bandit SUCCESS in 10m 12s :heavy_check_mark: fi-tox-diff-cover SUCCESS in 10m 59s