Add Unicode Copyright symbol to Copyright notice

[ann0see]

Short description of changes

Changes the Copyright symbol to the unicode equivalent

CHANGELOG: SKIP

Context: Fixes an issue?

Fixes: #2903
Does this change need documentation? What needs to be documented and how?

No.

Status of this Pull Request
Ready for review.

What is missing until this pull request can be merged?

Nothing.

Checklist

• I've verified that this Pull Request follows the general code principles
• I tested my code and it does what I want
• My code follows the style guide
• I waited some time after this Pull Request was opened and all GitHub checks completed without errors.
• I've filled all the content above

[pljones]

This doesn't address the start up banner, then?

 *** Copyright (C) 2005-2023 The Jamulus Development Team

Also, the © symbol can also be expressed (in the .ui file) as ©, I think, which might be easier to edit.
https://www.rapidtables.com/web/html/html-codes/html-code-copyright.html

[ann0see]

/usr/lib/qt5/bin/uic src/aboutdlgbase.ui -o ui_aboutdlgbase.h
uic: Error in line 72, column 34 : Entity 'copy' not declared.
File 'src/aboutdlgbase.ui' is not valid

I don't think so. I used ©

[ann0see]

Fixed the other situation too. I hope Windows supports unicode characters in terminal.

[ann0see]

I'm going to merge this now.