Fix grammar in docstrings (it's -> its)

[clevernt]

Description

incorrect grammar triggers me I'm sorry

Checklist

• [ ] If code changes were made then they have been tested.
  • [ ] I have updated the documentation to reflect the changes.
  • [ ] I have updated the changelog with a quick recap of my changes.
• [ ] This PR fixes an issue.
• [ ] This PR adds something new (e.g. new method or parameters).
• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed)
• [x] This PR is not a code change (e.g. documentation, README, ...)
• [x] I have read and agree to the Developer Certificate of Origin for this contribution