fix: update API spec for patching session environments

[leafty]

Closes #913, closes #985.

Update the API spec to allow null to be passed to reset args and command in session environments.

UI update: SwissDataScienceCenter/renku-ui#3888.

/deploy renku-ui=leafty/fix-session-env-api

[RenkuBot]

You can access the deployment of this PR at https://renku-ci-ds-1073.dev.renku.ch

[coveralls]

Pull Request Test Coverage Report for Build 18943682560

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 15 of 15 (100.0%) changed or added relevant lines in 3 files are covered.
• 14 unchanged lines in 6 files lost coverage.
• Overall coverage decreased (-0.04%) to 86.796%

---

Files with Coverage Reduction	New Missed Lines	%
components/renku_data_services/base_api/error_handler.py	1	87.5%
components/renku_data_services/crc/core.py	1	78.49%
components/renku_data_services/session/models.py	1	95.33%
components/renku_data_services/storage/blueprints.py	2	91.06%
components/renku_data_services/k8s/db.py	4	90.98%
components/renku_data_services/k8s/watcher/core.py	5	80.13%

Totals
Change from base Build 18941004583:	-0.04%
Covered Lines:	22724
Relevant Lines:	26181

---

💛 - Coveralls

[eikek]

Are these "not nullable" ones still used?

[leafty]

Yes, for the responses and for the POST payloads.

[RenkuBot]

Tearing down the temporary RenkuLab deployment for this PR.