Do not pollute component directory.

--- xmlschema-4.3.1/tox.ini.orig
+++ xmlschema-4.3.1/tox.ini
@@ -5,7 +5,6 @@
           mypy-py{310,311,312,313,314,315,py3},
           docs, ep51, coverage, pytest, w3c-xsdtests
 skip_missing_interpreters = true
-work_dir = {tox_root}/../.tox/xmlschema
 
 [testenv]
 deps =