ci(tox): Add isolated_build = true for pyproject.toml support

ERROR: pyproject.toml file found.
To use a PEP 517 build-backend you are required to configure tox to use an isolated_build:
https://tox.readthedocs.io/en/latest/example/package.html

tox.ini

@@ -1,6 +1,7 @@
 # For more information about tox, see https://tox.readthedocs.io/en/latest/
 [tox]
 envlist = py37,py38,py39,py310,py311,ci-py
+isolated_build = true
 
 [testenv]
 deps =