refactor(config)!: remove legacy config paths (amperser#1472)

BREAKING CHANGE:

The legacy configuration paths for global configuration
(`/etc/proselintrc`) and home configuration `~/.proselintrc.json` are no
longer read. Please relocate any configuration you wish to keep to
`$XDG_CONFIG_HOME/proselint/config.json`.

Author: Nytelife26

proselint/config/paths.py

@@ -17,13 +17,10 @@ def _get_xdg_path(env_var: str, default: Path) -> Path:
     return Path(xdg_path) if (xdg_path := os.environ.get(env_var)) else default
 
 
-config_global_path = Path("/etc/proselintrc")
 config_user_path = _get_xdg_path(XDG_CONFIG_VAR, home_path / ".config")
 
 config_paths = [
     # NOTE: This is in reverse priority order - the order config gets merged in
-    config_global_path,
-    home_path / ".proselintrc.json",
     config_user_path / "proselint" / "config.json",
     cwd / ".proselintrc.json",
 ]