fix(src): update the suggestion when headers are invalid

[frgfm]

This PR updates the suggestion in the error message from:

Your header should look like:

# Copyright (C) 2023-2024, Pyronear.

# This program is licensed under the Apache License 2.0.

to

Your header should look like:

# Copyright (C) <FILE_CREATION_YEAR>-2024, Pyronear.

# This program is licensed under the Apache License 2.0.

or if the project creation year is the current one:

Your header should look like:

# Copyright (C) <FILE_CREATION_YEAR>, Pyronear.

# This program is licensed under the Apache License 2.0.

Closes #17