Non utf-8 JS files become utf-8 files

[spfmoby]

Describe the bug
When you minify a .js file which is for example in the windows-1252 format, le .min.js file has a utf-8 format

To Reproduce
Steps to reproduce the behavior:

1. Create or open a JS file
2. convert it in windows-1252 format and save it
3. right click somewhere in the content of the .js file and select "Minify: Document"
4. The .min.js file has been created with the utf-8 format.

Expected behavior
The .min.js file should have the same encoding format as the source file.

Desktop (please complete the following information):

• OS: Windows 10 / VSCODE 1.62.3
• JS &CSS Minifier Version : 2.7.0 (latest)