chore(packaging): Remove redundant wheel dep from pyproject.toml (#671)

Remove the redundant `wheel` dependency, as it is added by the backend
automatically.  Listing it explicitly in the documentation was
a historical mistake and has been fixed since, see:
pypa/setuptools@f7d30a9

Signed-off-by: Michał Górny <[email protected]>

Author: mgorny

pyproject.toml

@@ -2,5 +2,4 @@
 build-backend = 'setuptools.build_meta'
 requires = [
     'setuptools >= 46.4.0',
-    'wheel'
-]
+]