feat: Add support for acceptSourceChanges in string-based MergeBranch API

[vinayakkamatcodes]

This PR adds the optional acceptSourceChanges parameter to the MergeBranchRequest TypedDict for the string-based API. Resolves #217

[Copilot]

Pull Request Overview

This PR adds a new field acceptSourceChanges to the MergeBranchRequest TypedDict class, expanding the merge branch request parameters to support accepting source changes during branch merging operations.

• Added acceptSourceChanges boolean field to MergeBranchRequest typed dictionary

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[Copilot]

The acceptSourceChanges field should be typed as Optional[bool] to maintain consistency with other optional fields in the MergeBranchRequest class (deleteAfterMerge and dryRun). Unless this is a required field, making it optional would provide a more flexible API design.

Suggested change

	acceptSourceChanges: bool
	acceptSourceChanges: Optional[bool]

[andrii-bodnar]

@vinayakkamatcodes please address the comment above so I can merge the PR

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.35%. Comparing base (b6d9323) to head (afba9fe).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #221      +/-   ##
==========================================
+ Coverage   99.35%   99.35%   +0.01%     
==========================================
  Files         178      178              
  Lines        8216     8217       +1     
  Branches      185      185              
==========================================
+ Hits         8162     8163       +1     
  Misses         39       39              
  Partials       15       15              

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