Fix `sync.py` for `lock.json` existing but empty

[blakeNaccarato]

Description

Motivation and context

Test plan

Checklist

• [x] My code follows this project's code style.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] My change is adequately tested.

Terms

• [x] My contribution follows the contributing guide.
• [x] I agree to follow the code of conduct.

Summary by Sourcery

This pull request addresses a bug in sync.py where the script would fail if lock.json existed but was empty. It also includes the removal of unused lock files and updates the changelog to document the fix.

• Bug Fixes:
  • Fixed an issue in sync.py where the script would fail if lock.json existed but was empty.
• Documentation:
  • Added a changelog entry for the fix in sync.py regarding the empty lock.json issue.
• Chores:
  • Deleted unused lock-high.json and lock.json files from the template directory.

[sourcery-ai[bot]]

Reviewer's Guide by Sourcery

This pull request addresses an issue in sync.py where the script fails if lock.json exists but is empty. The changes include modifying the condition to check for an empty lock.json, adding a changelog entry, and removing obsolete lock files.

File-Level Changes

Files	Changes
template/lock-high.json template/lock.json	Removed obsolete lock files to clean up the template directory.

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