Update dependency tox to v4

renovate[bot] · web-flow · commit f56dde5edf11 · 2023-08-17T17:53:14.000Z
diff --git a/requirements-dev.txt b/requirements-dev.txt
@@ -1,4 +1,4 @@
-tox==3.7.0
+tox==4.9.0
 pytest==4.3.0
 coverage==4.5.3
 mock==2.0.0
