`rationalize` incorrect for `Float16` input

[nsajko]

Converting the input to Float64 first seems to be a workaround:

julia> setprecision(2^15)
32768

julia> x = Float16(0.000488)
Float16(0.000488)

julia> rx = rationalize(BigInt, x, tol = false)
2047//4196351

julia> Float64(abs(rx - x))
2.3806961713130745e-7

julia> y = Float64(x)
0.00048804283142089844

julia> ry = rationalize(BigInt, y, tol = false)
2047//4194304

julia> Float64(abs(ry - x))
0.0

julia> Float64(abs(ry - y))
0.0

julia> versioninfo()
Julia Version 1.10.0-DEV.1221
Commit 9201414b3d8 (2023-05-05 17:36 UTC)
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 8 × AMD Ryzen 3 5300U with Radeon Graphics
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.6 (ORCJIT, znver2)
  Threads: 1 on 8 virtual cores