Add version option

tests/cli/test_cli.py

@@ -0,0 +1,10 @@
+from click.testing import CliRunner
+
+import textual
+from textual.cli.cli import run
+
+
+def test_cli_version():
+    runner = CliRunner()
+    result = runner.invoke(run, ["--version"])
+    assert textual.__version__ in result.output, "You need to update __version__"