Remove references to GPL since we now use a different license

Created by: jmitrevs

Description

Remove comments that refer to the GPL, since we now use a different license (and specify it globally)

Type of change

• Other (Specify)

Tests

Just removed comments, so no new tests are needed

Checklist

• I have read the guidelines for contributing.
• My changes generate no new warnings.
• I have installed and run pre-commit on the files I edited or added.
• I have added tests that prove my fix is effective or that my feature works.