update nthreads info in versioninfo (#52423)
Fixes https://github.com/JuliaLang/julia/issues/52404
@nilshg I opted to make it one line as it fits.
```
julia> versioninfo()
Julia Version 1.11.0-DEV.1011
Commit bb7091c6f2* (2023-12-04 14:58 UTC)
Platform Info:
OS: macOS (arm64-apple-darwin23.0.0)
CPU: 10 × Apple M2 Pro
WORD_SIZE: 64
LLVM: libLLVM-15.0.7 (ORCJIT, apple-m1)
Threads: 1 default, 0 interactive, 1 GC (on 6 virtual cores)
Environment:
JULIA_EDITOR = code
```
