Fix invalid TreeChanges in concurrent Tree.Style

[humdrum]

What this PR does / why we need it?

Fix invalid TreeChanges in concurrent Tree.Style

Any background context you want to provide?

What are the relevant tickets?

Related to yorkie-team/yorkie-android-sdk#149

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Additional documentation:

Checklist:

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

Attention: 111 lines in your changes are missing coverage. Please review.

Comparison is base (b1d58ea) 42.58% compared to head (c9200aa) 42.47%.
Report is 3 commits behind head on main.

Files	Patch %	Lines
Tests/Integration/TreeIntegrationTests.swift	0.00%	99 Missing ⚠️
Sources/Document/CRDT/CRDTTree.swift	0.00%	10 Missing ⚠️
Sources/Document/Json/JSONTree.swift	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #146      +/-   ##
==========================================
- Coverage   42.58%   42.47%   -0.12%     
==========================================
  Files         104      104              
  Lines       24276    24340      +64     
==========================================
  Hits        10338    10338              
- Misses      13938    14002      +64     

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