Lucene-Net-Website.yml: Don't persist checkout credentials on PR branch

[NightOwl888]

…hen checking out PR branch

• You've read the Contributor Guide and Code of Conduct.
• You've included unit or integration tests for your change, where applicable.
• You've included inline docs for your change, where applicable.
• There's an open issue for the PR that you are making. If you'd like to propose a change, please open an issue to discuss the change or find an existing issue.

Lucene-Net-Website.yml: Don't persist checkout credentials on PR branch

Description

This is among a series of issues yet to be fixed in the website build automation. This is an attempt to get the create-pull-request task to work. It is failing due to duplicate authorization headers and per ChatGPT, not persisting the credentials from checking out the branch is probably a fix.