Use importlib instead of pkg_resources

fierce/fierce.py

@@ -59,23 +59,21 @@ def find_subdomain_list_file(filename):
         return os.path.abspath(filename_path)
 
     try:
-        import pkg_resources
+        import importlib
     except ImportError:
         return filename
 
     # If the relative check failed then attempt to find the list file
     # in the pip package directory. This will typically happen on pip package
     # installs (duh)
-    package_filename_path = os.path.join("lists", filename)
     try:
-        full_package_path = pkg_resources.resource_filename(
-            "fierce",
-            package_filename_path
-        )
+        # Use importlib.resources.as_file when Python 3.9 is minimum version
+        full_package_path = importlib.resources.path("fierce.lists", filename)
     except ImportError:
         return filename
 
-    return full_package_path
+    with full_package_path as path:
+        return str(path)
 
 
 def head_request(url, timeout=2):