Updated nox: Run all Python tests, coverage and lint by default

noxfile.py

@@ -16,10 +16,10 @@
 import shutil
 import nox
 
-_PY_VERSIONS = ('3.7', '3.8', '3.9', '3.10', '3.11', '3.12', 'pypy3')
+_PY_VERSIONS = ('3.5', '3.6', '3.7', '3.8', '3.9', '3.10', '3.11', '3.12', 'pypy3')
 _PY_DEFAULT_VERSION = sys.version[:4]
 
-nox.options.sessions = ['test-{}'.format(_PY_DEFAULT_VERSION), 'test-pypy3']
+nox.options.sessions = chain(['test-{}'.format(version) for version in _PY_VERSIONS], ['coverage', 'lint'])
 
 
 @nox.session(python=_PY_VERSIONS)
@@ -59,6 +59,7 @@ def coverage(session):
     """\
     Run coverage.
     """
+    session.install('-Ur', 'tests/requirements.txt')
     session.install('.')
     html_output_dir = os.path.abspath(os.path.join(session.create_tmp(), 'html'))
     session.run('pytest', '--cov=segno', '--cov-report=term', '--cov-report=html:%s' % html_output_dir)