Adjust trimming test to JSON.jl ≥1.0

[topolarity]

Adapt to major update of JSON.jl: JuliaIO/JSON.jl#374

[quinnj]

Oh hey, didn't realize there was a test on JSON for trimming here! I did run through a few trimming toy executables and made a few tweaks in the new 1.0 release to ensure trim verify worked. I think doing a plain JSON.parse(json) then accessing abi["functions"] might not work though because the return of JSON.parse (untyped) is essentially Union{JSON.Object{String,Any},Vector{Any},String,Int64,Float64,BigInt,BigFloat,Bool,Nothing}, so you might need an assert on the expected type you get out? I'm also a noob at trimming (first time trying it out was yesterday!) so feel free to ignore if I'm spouting nonsense.

[topolarity]

This is not the trimmed executable itself, just a script that verifies the output of the trimmed program / JuliaC 😁