fix: syntax error for enum type

[BipulLamsal]

fix for the issue #1536

[ghaith]

Hello @BipulLamsal Thank you for the contribution. Do you mind adding some tests to the changes? To make sure the intended behavior is now being triggered. That is, we need to allow assignments to pass correctly, but we should get a syntax error when we use the = sign.

You can look at our parser tests to add a new test there. I activated the workflow on our side but you can also activate the workflow in your branch to make sure the code compiles and tests correctly.