Minimum version of treetable in requirements.txt

## 🐛 Bug Report

I had treetable 0.1 installed and that gave an error `ModuleNotFoundError: No module named 'treetable.table'; 'treetable' is not a package
`, after upgrading to the latest version it worked. Update the requirements to to use treetable>=0.2.5.

Open requirements.txt and find the treetable dependency. Change its minimum version to 0.2.5 as requested, then verify that the requirements file contains the intended constraint and that the dependency can be installed successfully.

Written by the indexing model from the issue text.