Change utils.check_envvars() name & return type

It now throws an error if any of the given variables are undefined,
instead of returning them as a non-empty set[str].
This and the new name should make the intent clearer at the call site.
Clean up documentation
Remove chevron dependency

Injecting variables into the documentation templates
can be done using standard string formatting.
Remove type annotations

Mypy wasn't contributing much to this project,
and the type annotations reduced the readability of the code.
Make docs colour scheme more muted
Add task to upload the package to PyPI
Update installation command to use PyPI
Update package metadata for PyPI
Update development dependencies
Remove wiki task

The `wiki` branch and corresponding site at
<https://man.sr.ht/~javiljoen/yatte/> have also been deleted.
The manual.html page in the docs site is sufficient.

Obsolete references to Pandoc in the docs have also been removed.
Bump version -> 0.9.0
Enable running commands needing quoting with utils.run

This function now accepts a command as either a single string
or a list of strings.
If it's a list, the elements are quoted before sending it to the shell.

utils.mkdir and utils.cp can now accept paths that need to be quoted,
such as path names containing spaces.
Make compatible with Python 3.7

Specifying the types of elements of `dict` and `set`
is only supported since Python 3.9.
This changeset allows `yatte` to be run on Python >= 3.7.
(It might work on older versions too, but I haven't tested it,
since 3.7 is the oldest officially supported version.)
Switch to semantic versioning -> 0.8.0
Add mention of `just` to intro in docs
Fix development setup instructions in docs
Don't collapse blank lines in rendered docs

This improves the code formatting in `manual.html`
and makes the output more predictable.
Move TOC to top horizontal navbar in docs

The CSS and template have been simplified considerably,
and the footer now stays at the bottom of the page again.
(The latter behaviour got broken by the introduction of the
`div.measure` in the previous commit.)
75b62acf — goose-life 2 years ago
Fix scrolling & min width in docs

On narrow screens, <pre> blocks were not getting x-scrollbars,
preventing the body text from reflowing to fit in the viewport.