Update zh_locale.dart

[BenderBlog]

What does this PR do?

Per Unicode CLDR, in mainland China, Monday is the first day of the week.
For Hong Kong SAR, Macau SAR, and Taiwan, Sunday is the first day of the week, per Unicode CLDR.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Maintenance change (non-breaking change such as upgrading a dependency, refactoring, or making a lint fix)
• Documentation update
• Breaking change (a fix or feature that would cause existing functionality to change)

Checklist

• Wrote additional tests, if needed
• All tests have passed, you can find the scripts from the ./bin folder
• I have updated the documentation accordingly, if needed.

Additional Information

Check https://www.unicode.org/cldr/charts/44/supplemental/territory_information.html and search for China, and you will get my idea.

[jama5262]

Thanks for the contribution, I have also updated the test