Fix: Argument naming in pontos-update-header

[n-thumann]

What

This PR fixes the naming of the license argument. It is wrongfully accessed via license_id, so I specified a dest to store the license argument in.
An alternative approach would be to rename all occurrences to license. This however interferes with the built-in license() and hence makes pylint sad.

Why

To fix:

➜  pontos git:(main) poetry run pontos-update-header -d /tmp/test -l GPL-2.0-only    
 ℹ pontos-update-header
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/nthumann/Greenbone/pontos/pontos/updateheader/updateheader.py", line 388, in main
    _update_file(
  File "/home/nthumann/Greenbone/pontos/pontos/updateheader/updateheader.py", line 152, in _update_file
    parsed_args.license_id,
AttributeError: 'Namespace' object has no attribute 'license_id'. Did you mean: 'license'?

With this patch applied:

➜  pontos git:(fix_updateheader) poetry run pontos-update-header -d /tmp/test -l GPL-2.0-only
 ℹ pontos-update-header
/tmp/test/mgasa-2023-0001.nasl: Added license header.

References

Checklist

• Tests

[github-actions]

Conventional Commits Report

Type	Number
Bug Fixes	2

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