libfmt version conflict, again

[tkapias]

          Yeah, using the bundled version worked. Thanks

Originally posted by @Dromader2137 in #271 (comment)

I'm building abaddon on Debian testing (Trixie) with FMT v9 from APT.
But, 2 other projects (kemai and ueberzugpp) are already present on my system, compiled and installed in /usr/local, with FMT v10.

This result in the same error as in issue 271: after 100%, ld fails because of FMT v10.

How can I force the correct version? -DSPDLOG_FMT_EXTERNAL=ON did not work.