Do not install `tomli` for `Python>=3.11`

Now it is in sync with `setup.py` and `pyproject.toml`

test-requirements.txt

diff --git a/test-requirements.txt b/test-requirements.txt
index 7c4b3b8..769e665 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -15,4 +15,4 @@
 ruff==0.0.272  # must match version in .pre-commit-config.yaml
 setuptools>=65.5.1
 six
-tomli>=1.1.0
+tomli>=1.1.0; python_version<'3.11'