feat(cli): Add shiny --version (#1387)

Author: gadenbuie

shiny/_main.py

@@ -18,14 +18,15 @@
 
 import shiny
 
-from . import _autoreload, _hostenv, _static, _utils
+from . import __version__, _autoreload, _hostenv, _static, _utils
 from ._docstring import no_example
 from ._typing_extensions import NotRequired, TypedDict
 from .express import is_express_app
 from .express._utils import escape_to_var_name
 
 
 @click.group("main")
+@click.version_option(__version__)
 def main() -> None:
     pass