Fix wasm-test github action

[ianthomas23]

Now that we have the wasm-test github action setup, this PR fixes it so that it runs correctly. I've tried out in https://github.com/QuantStack/git2cpp/actions/runs/21750231424/job/62746038988 which gives:

============================= test session starts ==============================
platform linux -- Python 3.14.2, pytest-9.0.2, pluggy-1.6.0 -- /home/runner/micromamba/envs/git2cpp-wasm/bin/python3.14
cachedir: .pytest_cache
rootdir: /home/runner/work/git2cpp/git2cpp
configfile: .pytest.ini
plugins: base-url-2.1.0, playwright-0.7.2, anyio-4.12.1
collecting ... collected 102 items

test_add.py::test_add[chromium-] PASSED                                  [  0%]
test_add.py::test_add_nogit[chromium] PASSED                             [  1%]
test_branch.py::test_branch_list[chromium] PASSED                        [  2%]
test_branch.py::test_branch_create_delete[chromium] PASSED               [  3%]

<snip>

test_status.py::test_status_add_file[chromium---long-] PASSED            [ 96%]
test_status.py::test_status_new_file[chromium---long--s] PASSED          [ 97%]
test_status.py::test_status_add_file[chromium---long--s] PASSED          [ 98%]
test_status.py::test_status_new_file[chromium---long---short] PASSED     [ 99%]
test_status.py::test_status_add_file[chromium---long---short] PASSED     [100%]

==================================== PASSES ====================================
======================= 102 passed in 206.24s (0:03:26) ========================
Built target test