Prevents Unicode decode errors in TTS text file upload

[6Morpheus6]

Open text file with utf-8 encoding

Added utf-8 encoding when opening a text file upladed in tts tab to prevent unicode errors

Description

Motivation and Context

Text upload fails if the text file contains non-unicode letters. Explicit utf-8 encoding when opening the file fixes this issue.

How has this been tested?

Uploading a file with non-unicode letters resulted in a UnicodeDecodeError

Screenshots (if appropriate):

Types of changes

• [x] Bug fix (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)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.