Add en_GB and en_US

Fixes python-humanize#210

Author: 2br-2b

Diff for: src/humanize/i18n.py

@@ -63,6 +63,9 @@ def activate(locale: str, path: str | None = None) -> gettext_module.NullTransla
     Raises:
         Exception: If humanize cannot find the locale folder.
     """
+    if locale == "en_GB" or locale == "en_US":
+        locale = None
+    
     if path is None:
         path = _get_default_locale_path()