Use the main branch from pypa/build rather than the fork.

Author: domdfcoding

tox.ini

@@ -40,7 +40,7 @@ skip_install = True
 changedir = {toxinidir}
 deps =
     virtualenv
-    git+https://github.com/domdfcoding/build@issue-250
+    git+https://github.com/pypa/build
     check-wheel-contents>=0.1.0
     twine>=3.2.0
 commands =