tox: set a $HOME value, helps conda install

Author: mr-c

tox.ini

@@ -57,7 +57,8 @@ deps =
   py312-lintreadme: readme_renderer[rst]
 
 setenv =
-  py3{8,9,10,11,12}-unit: LC_ALL = C.UTF-8
+  LC_ALL = C.UTF-8
+  HOME = {envtmpdir}
 
 commands_pre =
   py3{8,9,10,11,12}-unit: python -m pip install -U pip setuptools wheel