Working on Deprecate SumTo1 Transform

[nyeshlur]

Description

FutureWarning when users access sumto1 transform to let them know it's deprecated and will be removed in the future, and a test that verified the warning is working but you can still access it

Related Issue

• Closes issue: Deprecate SumTo1 Transform #7009

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks)

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):

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📚 Documentation preview 📚: https://pymc--7059.org.readthedocs.build/en/7059/

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