Linking to just `/3/` is admittedly risky, because item/anchor locations
can change across Python versions. Bumping the links from 3.7 to 3.11
gives us a few more years of not needing to touch them.

Can't drop the `importlib_metadata` requirement yet, though. We use some
stuff elsewhere that isn't stable in stdlib until py3.10.

Played with using intentionally wrong types in the definition of a
`PluginMetaDescription` and running `mypy` against it, but didn't see
any (new) errors flagged over that. Maybe I did it wrong, but it took
enough work shuffling docstrings around that I'm committing this anyway.

The test covering `_chunks()` still passes, so hooray!

Regular `dict` is promised to maintain insertion order as of Python 3.7
(which means this could have been done sooner, but it got forgotten, so
we're doing it at the point of dropping Python <3.8 instead).

Not doing exactly as the comment says because different Rule subclasses
pass aliases as either tuple or list depending on how whoever wrote the
subclass was feeling that day.

Instead, let's simplify the code to do everything in one step, and
unpack the `aliases` iterable so its type won't even matter.

Co-authored-by: SnoopJ <[email protected]>

`importlib.metadata` officially starts existing in Python 3.8, and we
are removing support for Python 3.7 before Sopel 8's stable release.
That means we can use the stdlib approach here to get the version string
for an entry-point plugin, and drop another `import importlib_metadata`.

I can't wait for Python 3.9's EOL... We can remove `importlib_metadata`
completely then.

As of Python 3.5, we can do this. It's overdue.

importlib.metadata.EntryPoint *shouldn't* differ from Python 3.8 onward,
unless there's something missing from the documentation. If this breaks
stuff on older Python releases (I'm on 3.10 locally), we will defer this
change until we drop 3.9 as planned per the code comments.