Fix nox venv reuse issue

[BrianMichell]

Command nox -s tests-3.13 would generate the below error if the nox environment already existed.

nox > Running session tests-3.13
nox > Creating virtual environment (uv) using python3.13 in .nox/tests-3-13
nox > Command uv venv -p python3.13 /home/source/mdio-python/.nox/tests-3-13 failed with exit code 2:
nox > Using CPython 3.13.9
Creating virtual environment at: .nox/tests-3-13
error: Failed to create virtual environment
  Caused by: A virtual environment already exists at `/home/source/mdio-python/.nox/tests-3-13`. Use `--clear` to replace it

nox > Session tests-3.13 failed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.55%. Comparing base (c3ba558) to head (d044428).
⚠️ Report is 230 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #811      +/-   ##
==========================================
+ Coverage   85.30%   89.55%   +4.24%     
==========================================
  Files          46      104      +58     
  Lines        2219     6135    +3916     
  Branches      306      408     +102     
==========================================
+ Hits         1893     5494    +3601     
- Misses        281      543     +262     
- Partials       45       98      +53     

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