fix venv

[mamico]

Try to fix GHA failures like

https://github.com/collective/pas.plugins.oidc/actions/runs/23942281322/job/69830994448

+ echo '==> Install environment'
+ uv venv /home/runner/work/pas.plugins.oidc/pas.plugins.oidc/.venv
==> Install environment
Using CPython 3.10.20
Creating virtual environment at: .venv
error: Failed to create virtual environment
  Caused by: A virtual environment already exists at `/home/runner/work/pas.plugins.oidc/pas.plugins.oidc/.venv`. Use `--clear` to replace it
make: *** [Makefile:76: /home/runner/work/pas.plugins.oidc/pas.plugins.oidc/.venv] Error 2
Error: Process completed with exit code 2.