Add missing license headers

[TimPansino]

Overview

• License headers were missing from several .py files.
• Useful command for finding these grep -r -L "Licensed under the Apache License" **/*.py

[github-actions]

Mega-Linter status: ❌ ERROR

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ PYTHON	bandit	14		0	0.48s
✅ PYTHON	black	14	5	0	0.54s
❌ PYTHON	flake8	14		4	0.41s
✅ PYTHON	isort	14	5	0	0.18s
❌ PYTHON	pylint	14		9	8.41s

See errors details in artifact Mega-Linter reports on GitHub Action page
Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff