Update fmt to fix MSVC C4996 warning

[ghost]

This PR updates the fmt library to resolve the MSVC C4996 deprecation warning, as highlighted in issue #3540 from the fmtlib repo.

Reference: Issue #2987

[gabime]

Thanks. Please submit the PR to the fmtlib repo insread.

[ghost]

I apologize for not explaining my intention clearly. The purpose of this PR was to update the embedded fmt library within spdlog to its latest version, which resolves the MSVC C4996 warning. I wasn't attempting to modify the fmt library itself, but rather to update spdlog's bundled version of fmt. This update aims to address the issue mentioned in spdlog#2987. I'm sorry for any confusion this may have caused.

I'm glad to see that the update seems to be working well now and the warning issue has been resolved. This is the outcome I was hoping for.