Fix character type in lambda functions

[diffusion4812]

Updated lambda functions in rapidcsv.h to use unsigned char instead of int for parameters in std::all_of and std::find_if. This prevents crashing/exception generation when attempting to parse unsupported (non-CSV) file types.

[d99kris]

Hi @diffusion4812 - thanks for contributing. Could you share an example file which causes the crashing/exception?

So that I can add a test once the fix is merged.

[diffusion4812]

Hi, here is a file that fails to parse.
testfile.csv

[d99kris]

Great, thanks, will try review the PR soon.

[d99kris]

Hi again, I was not able to reproduce any crash using the provided file, tested both on Mac/Clang Arm and Linux/GCC Arm. I tested with pTrim = true in SeparatorParams. Are there any other parameters needed to reproduce it, or special environment?

Anyway, the fix is correct as far as I can tell, so I will proceed to merge it. But if you have more details on how to reproduce the crash it's very appreciated, so that I can put in place a test case for catching regressions.

Thanks for contributing!