tox: remove isolated_build setting

bluetech · bluetech · commit 66429cef4c3b · 2025-10-24T12:38:01.000+03:00
According to https://tox.wiki/en/stable/upgrading.html#removed-tox-ini-keys: "Isolated builds are now always used."
diff --git a/tox.ini b/tox.ini
@@ -1,5 +1,4 @@
 [tox]
-isolated_build = True
 requires =
     tox >= 4
 envlist =
