Selenium and ToolShed test suites stuck with uvicorn 0.28.0

[nsoranzo]

Describe the bug
First noticed in #17653 :

Integration Selenium: https://github.com/galaxyproject/galaxy/actions/runs/8224077107/job/22487575262
Selenium: https://github.com/galaxyproject/galaxy/actions/runs/8224077110/job/22487574093
ToolShed: https://github.com/galaxyproject/galaxy/actions/runs/8224077095

It looks like some thread hangs when we shutdown the test server.

I have bisected the changes between uvicorn 0.27.1 and 0.28.0, which pointed to encode/uvicorn@1e5f1be as the commit introducing the issue.

Galaxy Version and/or server at which you observed the bug
Galaxy Version: dev

To Reproduce
Steps to reproduce the behavior:

1. Change the uvicorn requirement to 0.28.0 in lib/galaxy/dependencies/pinned-requirements.txt
2. TOOL_SHED_API_VERSION=v1 TOOL_SHED_TEST_BROWSER=twill ./run_tests.sh -toolshed lib/tool_shed/test/functional/test_0000_basic_repository_features.py (similarly for Selenium and Integration Selenium tests)
3. Tests pass but the test suite stops around 100% and needs to be killed with Ctrl+C

Expected behavior
Test suites succeed and exit.

[nsoranzo]

This will likely be fixed by encode/uvicorn#2276 .

[nsoranzo]

Fixed in uvicorn 0.29.0 .