Replace invalid copyright signs [C]

[swastkk]

Fixes #3659

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

[swastkk]

After adding the tests

=========================================== FAILURES ===========================================
__________________________ TestTextPreparation.test_invaild_copyright __________________________

self = <test_copyrights_basic.TestTextPreparation testMethod=test_invaild_copyright>

    def test_invaild_copyright(self):
        cp= '[C] The Regents of the University of Michigan'
        result= copyrights.prepare_text_line(cp)
>       assert result == 'Copyright (C) The Regents of the University of Michigan'
E       AssertionError: assert 'C The Regent...y of Michigan' == 'Copyright (C...y of Michigan'
E         - Copyright (C) The Regents of the University of Michigan
E         ?  ------------
E         + Copyright C The Regents of the University of Michigan

test_copyrights_basic.py:37: AssertionError
___________________ TestTextPreparation.test_invaild_copyright_insensitivity ___________________

self = <test_copyrights_basic.TestTextPreparation testMethod=test_invaild_copyright_insensitivity>

    def test_invaild_copyright_insensitivity(self):
        cp= '[c] The Regents of the University of Michigan and Merit Network, Inc. 1992,'
        result= copyrights.prepare_text_line(cp)
        print(result)
>       assert result== '(c) The Regents of the University of Michigan and Merit Network, Inc. 1992,'
E       AssertionError: assert 'c The Regent...k, Inc. 1992,' == '(c) The Rege...k, Inc. 1992,'
E         - (c) The Regents of the University of Michigan and Merit Network, Inc. 1992,
E         ? - -
E         + c The Regents of the University of Michigan and Merit Network, Inc. 1992,

test_copyrights_basic.py:43: AssertionError
------------------------------------- Captured stdout call -------------------------------------
c The Regents of the University of Michigan and Merit Network, Inc. 1992,
=================================== short test summary info ====================================
FAILED test_copyrights_basic.py::TestTextPreparation::test_invaild_copyright - AssertionError...
FAILED test_copyrights_basic.py::TestTextPreparation::test_invaild_copyright_insensitivity - ...
================================= 2 failed, 52 passed in 2.46s =================================

[pombredanne]

Some nit pickings to fix and then next step will be to fix this proper.