Wrap raw HTML in StringIO for pd.read_html (#726)

[SaguaroDev]

Closes #726.

Summary

pd.read_html() on pandas 3.0 no longer accepts literal HTML strings; they must be wrapped in io.StringIO. On pandas 2.x this currently emits:

FutureWarning: Passing literal html to 'read_html' is deprecated and will be
removed in a future version. To read from a literal string, wrap it in a
'StringIO' object.

A repo-wide search confirmed chainladder/core/tests/test_triangle.py::test_repr is the only call site passing raw HTML, so the fix is a single-line change. io was already imported in the file.

Verification

$ uv run pytest chainladder/core/tests/test_triangle.py::test_repr -W error::FutureWarning
2 passed
$ uv run pytest chainladder/core/tests/test_triangle.py
141 passed, 8 xfailed

Reference

• pandas 3.0 whatsnew (Other removals): https://pandas.pydata.org/docs/dev/whatsnew/v3.0.0.html#other-removals

[genedan]

Hi @SaguaroDev, this edit was already made in #729, which handles #664 along with its sub-issues. You're welcome to try solving any unassigned issues outside of #664 and its sub-issues, though.

[SaguaroDev]

Thanks @genedan — apologies for the duplicate, I missed #729 when scouting. Closing this in favor of the bundled fix there. Will look for unassigned issues outside the #664 tree.

[kennethshsu]

Thanks @SaguaroDev, and excellent attempt on your first PR! Welcome to the group! We look forward to your contributions!!!