fix: Update to user password should persist new sessionToken to Keychain

[cbaker6]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Approach

TODOs before merging

• Add tests
• Add entry to changelog

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (32a96a4) 91.65% compared to head (742e288) 91.71%.

Files	Patch %	Lines
Sources/ParseSwift/Objects/ParseUser.swift	97.44%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #147      +/-   ##
==========================================
+ Coverage   91.65%   91.71%   +0.06%     
==========================================
  Files         178      178              
  Lines       15511    15715     +204     
==========================================
+ Hits        14216    14413     +197     
- Misses       1295     1302       +7     

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