chore: adding NoneConst and None check

[Hashcode-Ankit]

Description

Fixes issue: https://github.com/pymc-devs/pymc/issues/7762

Related Issue

• [ ] Closes #
• [ ] Related to #

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)
• [ ] If you are a pro: each commit corresponds to a relevant logical change

Type of change

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

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📚 Documentation preview 📚: https://pymc--7764.org.readthedocs.build/en/7764/

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