codegen_tl1.py contains strange {{ and }}

[bmerkle]

I think there is a bug in utils/codegen_tl1.py regarding the usage of {. In the code always {{ and }} is used, but i think this is confusing/unnessary.

e.g. https://github.com/microsoft/BitNet/blob/5e39e75325db395285c8f2d84b6cdd6fa49bc27b/utils/codegen_tl1.py#L29

the generated headerfile then also contains {{ and }} of course

if you confirm that this syntax is kind of strange and we should fix it I could create a PR if you like