Remove redundant wheel dep from pyproject.toml

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

Author: mgorny

pyproject.toml

@@ -1,6 +1,5 @@
 [build-system]
 requires = ["setuptools",
-            "wheel",
             "setuptools_scm",
             "cython"]
 build-backend = 'setuptools.build_meta'