feat: Pyodide 0.28 release (#2487)

* Bump testing version to 0.28.0

* Bump Pyodide constraints

* Add Pyodide 0.28.0 identifier

* Override to a different, alpha version for testing

* Update docs for Pyodide versions everywhere

* Add comment on using older Pyodide alpha version

* Bump to `"cp313*"` for compatibility

* Drop identifier for Pyodide 0.28.0a3

* Add back Pyodide 0.28.0a3 identifier

* Add helpful comment about pyodide-prerelease option

* Fix test and add a comment about it

* Keep one Pyodide version per Python version

* Fix docs for `pyodide-prerelease`; Python ➡️ Pyodide

* Update utils.py

* Drop CI test step for overridden Pyodide version

Suggested-by: Joe Rickerby <joerick@mac.com>

---------

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

docs/platforms.md

@@ -172,7 +172,7 @@ You must target pyodide with `--platform pyodide` (or use `--only` on the identi
 
 It is also possible to target a specific Pyodide version by setting the [`pyodide-version`](options.md#pyodide-version) option to the desired version. Users are responsible for setting an appropriate Pyodide version according to the `pyodide-build` version. A list is available in Pyodide's [cross-build environments metadata file](https://github.com/pyodide/pyodide/blob/main/pyodide-cross-build-environments.json), which can be viewed more easily by installing `pyodide-build` from PyPI and using `pyodide xbuildenv search --all` to see a compatibility table.
 
-If there are pre-releases available for a newer Python version, the `pyodide-prerelease` [`enable`](options.md#enable) can be used to include pre-release versions.
+If there are pre-releases available for a newer Pyodide version, the `pyodide-prerelease` [`enable`](options.md#enable) can be used to include pre-release versions.
 
 ### Running tests