Remove version pin on pytest-timeout

Version pytest-timeout<2.0.0 still depends on distutils which doesn't
exist in debian bookworm anymore.

Author: luhenry

requirements-dev.txt

@@ -1,6 +1,3 @@
 pre-commit>=0.5.0
 pytest
-# TODO: This pin is to work around an issue where the system pytest is too old.
-# We should fix this by not depending on the system pytest/python packages at
-# some point.
-pytest-timeout<2.0.0
+pytest-timeout