Tests have good coverage but must be splitted.
Example test run:
```
pytest --log-cli-level=WARNING swh/lister/gitea/tests/
================================================= test session starts ==================================================
platform linux -- Python 3.7.3, pytest-6.2.1, py-1.10.0, pluggy-0.13.1
rootdir: /home/tenma/dev/swh-env/swh-lister, configfile: pytest.ini
plugins: hypothesis-6.0.1, flask-1.1.0, requests-mock-1.8.0, django-4.1.0, postgresql-2.5.2, forked-1.3.0, mock-3.5.1, asyncio-0.14.0, xdist-2.2.0, dash-1.18.1, cov-2.11.0, swh.journal-0.6.1, swh.core-0.11.1.dev4+g40018f2
collected 7 items
swh/lister/gitea/tests/test_lister.py::test_gitea_full_listing
---------------------------------------------------- live log call -----------------------------------------------------
WARNING swh.lister.gitea.lister:lister.py:90 Unexpected HTTP status code 429 on https://try.gitea.io/api/v1/repos/search?limit=3&order=asc&page=2&sort=id: b''
WARNING swh.lister.gitea.lister:before_sleep.py:45 Retrying swh.lister.gitea.lister.GiteaLister.page_request in 1.0 seconds as it raised HTTPError: 429 Client Error: None for url: https://try.gitea.io/api/v1/repos/search?limit=3&order=asc&page=2&sort=id.
PASSED [ 14%]
swh/lister/gitea/tests/test_lister.py::test_gitea_list_http_error[400]
---------------------------------------------------- live log call -----------------------------------------------------
WARNING swh.lister.gitea.lister:lister.py:90 Unexpected HTTP status code 400 on https://try.gitea.io/api/v1/repos/search?sort=id&order=asc&limit=3&page=1: b''
PASSED [ 28%]
swh/lister/gitea/tests/test_lister.py::test_gitea_list_http_error[500]
---------------------------------------------------- live log call -----------------------------------------------------
WARNING swh.lister.gitea.lister:lister.py:90 Unexpected HTTP status code 500 on https://try.gitea.io/api/v1/repos/search?sort=id&order=asc&limit=3&page=1: b''
PASSED [ 42%]
swh/lister/gitea/tests/test_lister.py::test_gitea_list_http_error[502]
---------------------------------------------------- live log call -----------------------------------------------------
WARNING swh.lister.gitea.lister:lister.py:90 Unexpected HTTP status code 502 on https://try.gitea.io/api/v1/repos/search?sort=id&order=asc&limit=3&page=1: b''
PASSED [ 57%]
swh/lister/gitea/tests/test_tasks.py::test_ping PASSED [ 71%]
swh/lister/gitea/tests/test_tasks.py::test_full_listing PASSED [ 85%]
swh/lister/gitea/tests/test_tasks.py::test_full_listing_params PASSED [100%]
================================================== 7 passed in 9.26s ===================================================
```