BLD: Pin cython for 37-locale build
Seeing if this resolves the build failure.

xref https://github.com/pandas-dev/pandas/issues/34704
Also the Checks and Docs github action builds are failing, and those use the main environment.yml I think? Thanks @TomAugspurger  Though looks like we still have this pinned here:

https://github.com/pandas-dev/pandas/blob/08febd2b9f77fd8f943de92939788e8bc53ee2d2/ci/deps/azure-37-numpydev.yaml#L17

I can push a follow up PR. We might not even need that any more @MeeseeksDev backport to 1.0.x Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

```
$ git checkout 1.0.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 a1191d6fb2d21631e1d4fb2c558d5c66c5ea3bdf
```

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

```
$ git commit -am 'Backport PR #34711: BLD: Pin cython for 37-locale build'
```

4. Push to a named branch :

```
git push YOURFORK 1.0.x:auto-backport-of-pr-34711-on-1.0.x
```

5. Create a PR against branch 1.0.x, I would have named this PR:

> "Backport PR #34711 on branch 1.0.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                 @jorisvandenbossche will do this next We actually don’t need to backport this can just do #34718