Added copyright notice to NOMAD fastapi sources.

nomad/app_fastapi/main.py

nomad/app_fastapi/models.py

nomad/app_fastapi/routers/auth.py

nomad/app_fastapi/routers/entries.py

nomad/app_fastapi/routers/users.py

nomad/app_fastapi/utils.py

tests/app_fastapi/routers/conftest.py

tests/app_fastapi/routers/test_auth.py

tests/app_fastapi/routers/test_entries.py

tests/app_fastapi/routers/test_users.py

tests/app_fastapi/test_utils.py