Enable flake8-bugbear linting and fix raised issues

Signed-off-by: Alfred Wingate <parona@protonmail.com>

src/euscan/handlers/__init__.py

@@ -13,7 +13,7 @@ from euscan import CONFIG, output
 handlers = {"package": [], "url": [], "all": {}}
 
 # autoimport all modules in this directory and append them to handlers list
-for loader, module_name, is_pkg in pkgutil.walk_packages(__path__):
+for loader, module_name, _is_pkg in pkgutil.walk_packages(__path__):
     module = loader.find_spec(module_name).loader.load_module(module_name)
     if not hasattr(module, "HANDLER_NAME"):
         continue