Fix nullable reference types warning

[nickiemc]

When building, the following warning is produced:

Languages/Python/Conversions.cs(29,74): warning CS8632: The annotation for nullable reference types should only be used in code within a '#nullable' annotations context. 

This warning should be addressed.

[mrbiggred]

@dan-hein I noticed that @nickiemc re-opened this case. Can you take a look to see if PR #213 actually fixed this issue or not? Thanks.

[dan-hein]

Hey @mrbiggred, I believe Nickie did that just to mark the task as Ready for Deployment. The changes attached should fix the issue described. I think that was mainly for the Freshli board.

[nickiemc]

@dan-hein @mrbiggred Correct. GitHub automatically closed the issue because of the Resolves keyword in PR #213. But since it still hasn't been deployed to production, I reopened it and moved to Ready for Deployment.