Add __main__ CLI hook to support local dev

This follows the convention for typer prorams. Note the same can
also be achieved with e.g.

        python -c 'from pms.cli import main; main()'

but having it run automatically saves documenting this.

Author: benthorner

src/pms/cli.py

@@ -131,3 +131,7 @@ def csv(
                 csv.write("time,sensor,hex\n")
             for raw in reader(raw=True):
                 csv.write(f"{raw.time},{sensor_name},{raw.hex}\n")
+
+
+if __name__ == "__main__":  # pragma: no cover
+    main()