chore: remove redundant pull request template

[nearlyforget]

Description

This PR removes the local pull_request_template.md file from the .github directory. Since the organization now has a central .github repository with a standardized pull request template, this local copy is redundant and will be automatically superseded by the organization-level version.

Type of change

• Documentation update (repository health files)

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Is this a Breaking Change or Removal?

• I have added ! to my PR title (Note: Only if you consider this a "breaking" removal of a file, but chore is usually sufficient here).
• I have added justification below.

Breaking Changes / Removal Justification

N/A - This is a non-functional change to repository metadata.

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Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

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