Use walrus operator and explicitly require python >= 3.8

Signed-off-by: Jean-Christophe Morin <jean_christophe_morin@hotmail.com>

nvchecker_source/pypi.py

@@ -20,7 +20,7 @@ async def get_version(name, conf, *, cache, **kwargs):
 
   for version in data['releases'].keys():
     # Skip versions that are marked as yanked.
-    if len(data['releases'][version]) != 0 and data['releases'][version][0]['yanked']:
+    if (vers := data['releases'][version]) and vers[0]['yanked']:
       continue
 
     try:

setup.cfg

@@ -39,10 +39,10 @@ classifiers =
 
 [options]
 zip_safe = True
+python_requires = >=3.8
 
 packages = find_namespace:
 install_requires =
-  setuptools; python_version<"3.8"
   tomli; python_version<"3.11"
   structlog
   platformdirs