Multiple-paragraph param descriptions not rendered correctly in the docs

[corranwebster]

Describe the bug

The documentation does not seem to be building parameter descriptions pulled from docstrings which contain multiple paragraphs or other constructs like lists inside a :param: block.

Steps to reproduce

Go to https://toga.beeware.org/en/latest/reference/api/widgets/tree/ and look at the "accessor" parameter.

The source for this looks like this:

toga/core/src/toga/widgets/tree.py

Lines 60 to 68 in d68561f

	:param accessors: Defines the attributes of the data source that will be used to
	populate each column. Must be either:
	* `None` to derive accessors from the headings, as described above; or
	* A list of the same size as `headings`, specifying the accessors for each
	heading. A value of [`None`][] will fall back to the default generated
	accessor; or
	* A dictionary mapping headings to accessors. Any missing headings will fall
	back to the default generated accessor.

Other multi-paragraph :param: blocks are similarly rendered as one paragraph.

Expected behavior

The markdown contained in the param description should be fully respected.

Screenshots

From the current website

Environment

• Operating System: All
• Python version: All
• Software versions:
  • Toga: current main branch

Logs

No response

Additional context

If it isn't possible to get this to work because the tools don't support it, then a number of docstrings probably need to be re-worked to put the deeper description of parameter behaviour in the body of the docstring.

[freakboy3742]

This is a known issue with mkdocstrings; we reported it as mkdocstrings/mkdocstrings#808, which has been fixed upstream and is awaiting a release. I guess we have a decision to make on whether we pin to a pre-release version of mkdocstrings in the short term. Any thoughts, @kattni?

[kattni]

We should pin to a commit hash that includes the fix for now.