correct contributing guidelines
@@ -49,7 +49,7 @@ Unfortunately, the command `tox -l` only returns the _default_ test builds. The
Basic usage of `tox` within this monorepo is:
-1. `pip install tox tox-monorepo`
+1. `pip install tox<4 tox-monorepo`
2. `cd` to target package folder
3. run `tox -c path/to/tox.ini`
