🐛 stdext::checked_array_iterator is being deprecated

[zach2good]

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Discussed in #4739

<div type='discussions-op-text'>

<sup>Originally posted by **Stammer6** November 18, 2023</sup>
Hi, everyone! I'm quite new to all of this, so bear with me. I followed the instructions to the letter, having tried now on two different computers (Windows 10 & 11), and on one of them twice. All three attempts have resulted in this error in VisualStudio 2022 while attempting to build the project.

Error code C2220 ...\server\build\x64-Debug\_deps\spdlog-src\include\spdlog\fmt\bundled\format.h (line 341)

Line 341 is as follows:
`template <typename T> using checked_ptr = stdext::checked_array_iterator<T*>;`

I've looked up similar issues before making this discussion, and I've tried making slight alterations to the line in question as well as lines around it. I've also formatted it to UTF-8 with BOM to see if that would help. No dice. I'd be grateful for some pointers.

Thanks in advance!</div>

fmtlib/fmt#3540
https://github.com/gabime/spdlog/blob/v1.x/CMakeLists.txt#L206-L209