Can't run wdls in a loop when importing miniwdl as a python package

[giuliovn]

When importing from WDL.CLI import runner and running wdl workflows as part of a python script in a loop, the second workflow can't start because of this error:

Traceback (most recent call last):
  File "/home/giulio/proj/ultima/mario/main.py", line 33, in <module>
    main(WDL_PATH, INPUTS)
  File "/home/giulio/proj/ultima/mario/main.py", line 16, in main
    out = wdl_run(
          ^^^^^^^^
  File "/home/giulio/proj/ultima/mario/.venv/lib/python3.12/site-packages/WDL/CLI.py", line 660, in runner
    set_status = cleanup.enter_context(configure_logger(json=log_json))
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/giulio/.local/share/uv/python/cpython-3.12.3-linux-x86_64-gnu/lib/python3.12/contextlib.py", line 526, in enter_context
    result = _enter(cm)
             ^^^^^^^^^^
  File "/home/giulio/.local/share/uv/python/cpython-3.12.3-linux-x86_64-gnu/lib/python3.12/contextlib.py", line 137, in __enter__
    return next(self.gen)
           ^^^^^^^^^^^^^^
  File "/home/giulio/proj/ultima/mario/.venv/lib/python3.12/site-packages/WDL/_util.py", line 432, in configure_logger
    coloredlogs.install(
  File "/home/giulio/proj/ultima/mario/.venv/lib/python3.12/site-packages/coloredlogs/__init__.py", line 457, in install
    handler = StandardErrorHandler()
              ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/giulio/proj/ultima/mario/.venv/lib/python3.12/site-packages/WDL/_util.py", line 374, in __init__
    assert not self.__class__._singleton
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError

If I remove the assertion assert not self.__class__._singleton everything seems to work fine, but I guess it is there for a reason.
The weirdest thing is that an equivalent setup worked until 2 weeks ago (I see the last instance ran 2024-11-08), and I can't spot any difference in the code, python interpreter and dependencies versions.

To reproduce

1. Clone https://github.com/giuliovn/mario.
2. Make sure commit 5b5d819a99b01429cb967199b128ecd5b455be3e is checked out
3. Follow the instruction in the repo's README.