update legit_r for click

With the introduction of click in commit ca8b6fc,
the entry point changes.
This commit updates legit_r accordingly,
otherwise the packaged exe on Windows will not work.

legit_r

@@ -4,4 +4,4 @@
 import legit.cli
 
 if __name__ == '__main__':
-    legit.cli.main()
+    legit.cli.cli()