Fix optimize example notebook folder name

[jessegrabowski]

Description

The name of the optimize folder was wrong (it was "optimization"), so the new notebook wasn't being displayed in the gallery. Oops.

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://pytensor--1474.org.readthedocs.build/en/1474/