Add setuptools to 'testing' extra packages

Signed-off-by: FeRD (Frank Dana) <ferdnyc@gmail.com>

Author: ferdnyc

setup.cfg

@@ -55,6 +55,7 @@ where = src
 
 [options.extras_require]
 testing =
+    setuptools >= 50
     pytest >= 6, != 7.0.0
     pytest-xdist >= 2
     aboutcode-toolkit >= 7.0.2