How to avoid deprecation notice for libraies supporting multi-version of Nim?

[shirleyquirk]

If "tables" isn't a defined as an identifier, you have more problems than just 
the deprecation 😂

Works for me on 0.16.0, 0.20.0, 1.0.0, 1.0.10, 1.2.0, 1.2.4,1.2.6, 1.2.8, 
1.4.0, and 1.5.1