Currently, the CMAKE script is able to aither use the system library, or download a bundle.
We don't have FMT as a system library in RHEL, and we can't *download* a bundle during build time.
So we download the bundle ourselves, add it as additional package sources, and redirect the CMAKE
so it would search for it on the correct - local - location.

--- mariadb-10.11.6/cmake/libfmt.cmake	2023-11-08 16:51:39.000000000 +0100
+++ mariadb-10.11.6/cmake/libfmt.cmake_patched	2024-01-10 17:29:18.004421343 +0100
@@ -15,7 +15,7 @@ MACRO(BUNDLE_LIBFMT)
   ExternalProject_Add(
     libfmt
     PREFIX   "${dir}"
-    URL      "https://github.com/fmtlib/fmt/archive/refs/tags/8.0.1.zip"
+    URL      "${CMAKE_BINARY_DIR}/bundles/8.0.1.zip"
     URL_MD5  e77873199e897ca9f780479ad68e25b1
     INSTALL_COMMAND ""
     CONFIGURE_COMMAND ""