Convertor of cli_tool not working #152

This is a follow-up of #148 (comment) .

I've tried running the convertor. But couldn't run it successfully for any of the ways defined in the README.md file.

The following are the ways I tried and the errors they've raised.

convertor --infile file.rdf --outfile output.json raised following error:
Error: Invalid value for '--to' / '-t': invalid choice: undefined. (choose from json, rdf, yaml, xml, tag)
convertor --from rdf file.rdf --to json output.json raised following error:
spdx.parsers.builderexceptions.FileTypeError: INPUT FILETYPE NOT SUPPORTED. (only RDF and TAG format supported)
convertor -f rdf file.rdf -o output.json raised following error:
Error: Invalid value for '--to' / '-t': invalid choice: undefined. (choose from json, rdf, yaml, xml, tag)

If you think I might've made some mistake while running the tool, you can check how I ran it in this google colab file