#213 Fix bug with {fmt} integration

[YarikTH]

This should be small

Small pull requests are great and easy for me to understand and accept
Please try prefix every commits in the pull request with Arlo's git notation

Prefix	Meaning
e	development enviroment only - not production
d	documentation only
t	tests only
R!!	Refactoring
B!!	Bug Fix
F!!	New Feature

But it's not small!

Then you should setup a remote pairing session with Llewellyn ( [email protected] )
Usually the sessions are between 45-90 minutes.

assuming you still feel it is small, please include

Description

See linked issue #213.

TL;DR {fmt} integration is triggered by FMT_VERSION define that is provided by <fmt/core.h>, while feature itself is using fmt::to_string() that is defined in <fmt/format.h> that causes a bug.

The solution

Include <fmt/format.h> in case {fmt} integration is triggered, so even if user included only <fmt/core.h>, the library provides itself with needed header to work correctly.

Notation

I prefer lots of very small commits prefixed with Arlo's git notation

[YarikTH]

Sorry, I made a commit before reading about Arlo git notation. I can modify its message if needed

[claremacrae]

Thank you very much indeed for this.

We are currently trying to get the builds passing again, after which we will test, review and merge this.

[YarikTH]

Any progress?