Restrict typing-extensions package to versions before v4.6.0

[GiaJordan]

This PR temporarily fixes the issue described in FDS-478 where tests would fail because of using isinstance() in the process of executing the code as normal.

From the typing-extensions changelog, in versions v4.6.0 and up (released May 22, 2023 so 3 days ago):

Backport python/cpython#26067 (originally by Yurii Karabas), ensuring that isinstance() calls on protocols raise TypeError when the protocol is not decorated with @runtime_checkable. Patch by Alex Waygood.

This matches the errors raised during tests when we updated our poetry.toml file and the dependencies in the .lock file were allowed to update as necessary.

Until our relevant classes or possibly in the python client are updated this will cause errors when we run our tests. Pinning the version gives us time to continue development on more pressing issues until we have the bandwidth to make updates to comply with the new requirements. typing-extensions was not a direct dependency for schematic beforehand, but was required by our dependencies so the version was relatively unlocked before this PR.

[milen-sage]

@GiaJordan I see docutils and mistune packages are removed from poetry.lock. It's likely the removal wouldn't have impact. Do you know why thy are no longer needed though?

[GiaJordan]

@milen-sage I'm not sure why they're no longer needed, I wouldn't have expected removals. However, it seems like when they were present they were extras. It could be that the new version of jupyter-server or jupyter-events doesn't need them anymore. I thought that functionality could possibly be handled by the newly added overrides package, but it looks like their functions aren't related.

[milen-sage]

Yes, this makes sense - thanks for checking!

[GiaJordan]

@milen-sage for sure!

[MiekoHash]

Also reported by Adam T via Slack here