generate_translations.py: Fix invalid escape sequences

[meator]

Invalid escape sequence \; is used in two places in the src/language/generate_translations.py file. This results in the following warnings appearing when someone tries to bytecompile Python (which is done automatically by some package managers):

./usr/lib/python3.12/site-packages/openshot_qt/language/generate_translations.py:2: SyntaxWarning: invalid escape sequence '\;'
  """
./usr/lib/python3.12/site-packages/openshot_qt/language/generate_translations.py:106: SyntaxWarning: invalid escape sequence '\;'
  subprocess.call('find %s -iname "*.py" -exec xgettext -j -o %s --keyword=_ {} \;' % (

This PR fixes this problem with r"" string literals.

This warning appears only in newer versions of Python.

[meator]

Oops, sorry for making a duplicate: #5592