Fix format conflict with std::format - #419

With these changes I can successfully compile ITensor using gcc-13.
Thank you for looking into this so quickly @mtfishman

@emstoudenmire any opinion on how to deal with the namespace clash of tinyformat::format, now that there is a std::format?

@Wentzell glad that helped, I guess at least you and others can use this branch with the newer compilers while we decide on a more permanent solution.

Thanks Matt, I think this is a good fix to just to not introduce format into the namespace. I think it's now better to leave it up to users whether they want to do something like using std::format; or using tfm::format; or just use the qualified names. Even though technically this is a breaking change, I think it's a very minor one in the sense of I wonder how many users were using format as introduced by ITensor?

format is being used in some examples so I imagine some people copied it from there. I'm ok making this change, as you say it's easy enough to tell people to add using tfm::format; at the top of their code.

I guess with the new website we've lost our "News" section where we used to announce new versions and breaking changes for C++ ITensor, would be nice to find a place to announce this on the website so we don't catch people off guard. We can also announce things like that on the Discourse forum. For Julia we just do it in the Julia docs and Github README.

@emstoudenmire would you be ready to make a post about this if I merge it soon? @Wentzell wants this merged so they can use the official ITensor version in their CI tests.

@emstoudenmire should I merge this?

I've added a News entry publicly about this now on https://itensor.org

Please have a look to let me know if it's accurate.

Thanks, looks great and that will be very helpful to have going forward! To be on the conservative side, I'm going to avoid introducing the tfm shorthand into the namespace by default, so users will have to use tinyformat::format. Could you change that "News" item appropriately? We could mention that the tfm shorthand can be used by defining:

namespace tfm = tinyformat;

@emstoudenmire I updated the News item already.

Thanks for updating it!