[clang] [Clang] Suppress a ``-Wimplicit-int-conversion``warning introduced in #126846 (PR #139429)

[via cfe-commits]

cor3ntin wrote:

If that warning is disruptive, maybe we should consider making it a separate warning that people can disable independently? It is certainly a potential source of bugs, so I'm not sure removing it entirely is the right approach  
@AaronBallman 

https://github.com/llvm/llvm-project/pull/139429