docs: Update developer documentation

[matthewfeickert]

Description

Following PR #1846, update the developer documentation to reflect the tbump workflow and general workflow updates.

Main bits:

• Update the developer docs to make some core dev team working knowledge explicit and hopefully make onboarding new developers easier.
• Advocate for use of SSH keys for GitHub, which is easier to suggest now that GitHub has removed password authentication.
  • c.f. https://github.blog/2021-09-01-improving-git-protocol-security-github/
• Split the testing section into writing and running tests and give explicit commands for running various types of tests.
• Describe the tbump tag generation procedure added in PR ci: Add bump version workflow for release tags #1846.
• Summarize deployment to TestPyPI and PyPI in a Deployment subsection under the Publishing section.

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

* Update the developer docs to make some core dev team working knowledge
explicit and hopefully make onboarding new developers easier.
* Advocate for use of SSH keys for GitHub, which is easier to suggest
now that GitHub has removed password authentication.
   - c.f. https://github.blog/2021-09-01-improving-git-protocol-security-github/
* Split the testing section into writing and running tests and give explicit
commands for running various types of tests.
* Describe the tbump tag generation procedure added in PR #1846.
* Summarize deployment to TestPyPI and PyPI in a Deployment subsection under
the Publishing section.

[codecov]

Codecov Report

Merging #1847 (c8e8a5d) into master (1cf0ac6) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1847   +/-   ##
=======================================
  Coverage   98.16%   98.16%           
=======================================
  Files          68       68           
  Lines        4315     4315           
  Branches      725      725           
=======================================
  Hits         4236     4236           
  Misses         46       46           
  Partials       33       33           

Flag	Coverage Δ
contrib	26.44% <ø> (ø)
doctest	60.78% <ø> (ø)
unittests-3.10	96.03% <ø> (ø)
unittests-3.7	96.02% <ø> (ø)

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[matthewfeickert]

Relevant RTD build page: https://pyhf--1847.org.readthedocs.build/en/1847/development.html

[matthewfeickert]

Something cool that I learned while writing this is that pytest-mpl has a --mpl-generate-summary html option that will make very nice comparison visuals for you!

So

pytest tests/contrib --mpl --mpl-baseline-path tests/contrib/baseline --mpl-generate-summary html

will make the following website

👍

@andrzejnovak did you know about this?

[andrzejnovak]

Neat, I think this is a new feature, at least since I've set up the test suite for mplhep.