Replace deprecated pkg_resources with importlib.resources

[tavallaie]

Fix deprecation warning by replacing pkg_resources.resource_filename with importlib.resources.files(), ensuring compatibility with future setuptools versions.
Python < 3.10 is EOL as of October 2025, so this change safely replaces pkg_resources with the standard importlib.resources.
This PR fix #10

[tavallaie]

@ZohaibAhmed @TediPapajorgji
knock knock, is there anybody who can review and merge the PR?

[tavallaie]

@ZohaibAhmed @TediPapajorgji
knock knock, is there anybody who can check the PR?

[johnmeade]

Hey, sorry for the delay, and thanks for submitting! Your change almost works, you just need to move the lines around, because PerthImplicitWatermarker attempts to import PREPACKAGED_MODELS_DIR.

ie this works:

from importlib.resources import files
PREPACKAGED_MODELS_DIR = files(__name__).joinpath("pretrained")
from .perth_net_implicit.perth_watermarker import PerthImplicitWatermarker