Add missing backticks to correct formatting

[crnsh]

📚 Description

matrix_modn_dense_float.pyx had single backticks in one of the docstrings which was causing it to render as LaTeX text, while it was intended to be monospace formatted. The missing backticks are added to fix this.

Fixes #35363

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies