Deprecate contentsheet

[gisellerosetta]

Proposed Changes

• Removes deprecation notice for the contentsheet attribute in write_workbook()
• Tests pass locally and I don't think it should break anything based on where else it appears appears.

Related Issues

• Fixes Deprecate contentsheet #299

Pre-requisites

This section may not be fully required if the branch is not merging into main.
Please indicate items that aren't necessary and why, with comments around incomplete checks.

• Version number has been incremented, according to SemVer NA
• Changelog has been updated, listing changes to this version. Use the keep a changelog format
• New features are tested
• New features are documented using the numpydoc docstring format NA
• Other relevant package documentation is updated
• For new functionality, examples are included in the docs or a feature request has
  been made for it/them. NA