fix: close annotation file handle via context manager

[tempoo04]

What does this PR do?

Fixes a resource leak in Project._annotation_params() where annotation_path was opened twice — once via a context
manager that did nothing, and again with a bare open() call whose handle was never closed.

Before:

 with open(annotation_path):
  annotation_string = open(annotation_path).read()

After:

with open(annotation_path) as f:
  annotation_string = f.read()

Related Issue(s): N/A

Type of Change

• Bug fix (non-breaking change that fixes an issue)

Testing

• I have tested this change locally
• I have added/updated tests for this change

Test details:
Manually verified annotation upload flow reads file content correctly with the fixed handle. No behavioral change —
fix only affects resource cleanup.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings or errors

Additional Context

File descriptor leak only matters under high-volume upload loops or on systems with low fd limits, but the fix also
removes the redundant open() call making the intent clearer.