Encoding issue on creation lines for htaccess file

[AleTorrisi]

Proposed changes

Scenario: use a not latin language (in example Chinese), then save permalinks. Default rules set by WordPress in the .htaccess file are wrong and cause 500 error.

The pull request wants fix this issue adding a needed encoding when the htaccess file is written again adding new rules.

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [] Documentation Update (if none of the other choices apply)

Checklist

• Linting and tests pass locally with my changes
• [] I have added tests that prove my fix is effective or that my feature works
• [] I have added necessary documentation (if appropriate)

Further comments