fix(ci): use python3 -m pip instead of bare pip for compatibility

On CentOS with source-compiled Python 3.10, 'pip' command may not be
in PATH. Use 'python3 -m pip' which works everywhere.

.gitea/workflows/ci-cd.yml

@@ -397,7 +397,7 @@ jobs:
         shell: sh
         run: |
           set -eu
- pip install -q pytest-rerunfailures
+ python3 -m pip install -q pytest-rerunfailures
           PYTHONPATH="$PWD/apps/api:$PWD" python3 -m coverage run --append \
             --source=apps/api/app,packages \
             --omit="*/migrations/*,*/tests/*,*/test_*.py,*/site-packages/*" \