[python] Check census version for get_all_available_embeddings

[ivirshup]

Fixes https://github.com/chanzuckerberg/cellxgene-census/issues/1202

I do have some concern about the test for get_embedding_metadata_by_name since it may break when "stable" updates if there are no embeddings for the new "stable" release.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.15%. Comparing base (8d1e103) to head (979f990).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1207 +/- ## ========================================== + Coverage 91.11% 91.15% +0.03% ========================================== Files 77 77 Lines 5923 5945 +22 ========================================== + Hits 5397 5419 +22 Misses 526 526 ``` | [Flag](https://app.codecov.io/gh/chanzuckerberg/cellxgene-census/pull/1207/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=chanzuckerberg) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/chanzuckerberg/cellxgene-census/pull/1207/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=chanzuckerberg) | `91.15% <100.00%> (+0.03%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=chanzuckerberg#carryforward-flags-in-the-pull-request-comment) to find out more.

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