fix: set build-backend in pyproject.toml

Remove wheel from build requirements and add proper
build-backend per PEP 517. This fixes the issue where
pip install would not use build isolation properly.

Fixes #1452

Author: Jah-yee

pyproject.toml

@@ -1,5 +1,6 @@
 [build-system]
-requires = ["setuptools", "wheel"]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
 
 [tool.cibuildwheel]
 enable = ["pypy"]