Remove ini_hex and ini_HEX on 1.6+

[ToucheSir]

Ref. JuliaLang/julia#32859, JuliaMath/DoubleFloats.jl#125. This is causing warnings downstream in CUDA.jl.

[codecov]

Codecov Report

Base: 61.00% // Head: 49.51% // Decreases project coverage by -11.48% ⚠️

Coverage data is based on head (7e7c81b) compared to base (0632885).
Patch coverage: 62.50% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           master      #37       +/-   ##
===========================================
- Coverage   61.00%   49.51%   -11.49%     
===========================================
  Files           4        3        -1     
  Lines         100      103        +3     
===========================================
- Hits           61       51       -10     
- Misses         39       52       +13     

Impacted Files	Coverage Δ
src/printf.jl	25.00% <62.50%> (-58.34%)	⬇️
src/bfloat16.jl	63.88% <0.00%> (-1.91%)	⬇️
src/BFloat16s.jl

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[ToucheSir]

Bump on this. One other thing I was considering was adding more versions to the test matrix (1.6 and latest stable), but didn't want to blow up the test matrix size too much. If there are any suggestions there, happy to add them to this or a follow-up PR.

[ToucheSir]

Bump again? This may be causing intermittent failures on FluxML CI: FluxML/Metalhead.jl#142

[ToucheSir]

Thanks @JeffreySarnoff !