Downgrade minimum traitlets version to 5.4

[danielhollas]

In #621 I've unpinned traitlets dependency from traitlets==5.9.0 to traitlets~=5.9. What I did not realize, and we found out the hard way in aiidalab/aiidalab-docker-stack#494, traitlets>=5.10 break the jupyter notebook version in the current AiiDAlab image.

As aiidalab/aiidalab-docker-stack#494 showed as, it is really not good if traitlets dependency is installed outside of the conda enviroment (i.e. to ~/.local) as it may break the jupyter notebook. Here we downgrade the minimum traitlets version back to 5.4.

(NOTE: That the original motivation to upgrading to 5.9 was performance, I believe it is better if we upgrade directly in the image). I'll open a separate issue for discussion, this is just a hotfix.

Fixes aiidalab/aiidalab-docker-stack#494

[codecov[bot]]

Codecov Report

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

Project coverage is 83.61%. Comparing base (de5f0cc) to head (34bbe53). Report is 10 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #629 +/- ## ======================================= Coverage 83.61% 83.61% ======================================= Files 16 16 Lines 3522 3522 ======================================= Hits 2945 2945 Misses 577 577 ``` | [Flag](https://app.codecov.io/gh/aiidalab/aiidalab-widgets-base/pull/629/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidalab) | Coverage Δ | | |---|---|---| | [python-3.11](https://app.codecov.io/gh/aiidalab/aiidalab-widgets-base/pull/629/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidalab) | `83.61% <ø> (ø)` | | | [python-3.9](https://app.codecov.io/gh/aiidalab/aiidalab-widgets-base/pull/629/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidalab) | `83.65% <ø> (ø)` | | 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=aiidalab#carryforward-flags-in-the-pull-request-comment) to find out more.

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[danielhollas]

Notebook failures are unrelated to this PR.

[danielhollas]

@edan-bainglass does this change make sense to you?