As indicated in the open issue [#1320](https://github.com/alire-project/alire/issues/1320) the detection of `gmp` does not work with `alr` with the Fedora Linux OS. This PR adds the suggested missing config line to detect the Fedora `gmp-devel` library.
Tested by editing the local cache file `~/.config/alire/indexes/community/repo/index/li/libgmp/libgmp-external.toml` to add the line suggested in the open issue:
```
fedora = ["gmp-devel"]
````
The detection then works as expected, and the previously failing build of `libadalang` on Fedora 38 (x86_64) now works.
Proper use of these packages would require calling `pkg-config` to set up
environment, which Alire does not do (yet?)
Co-authored-by: GHA <actions@github.com>
Also applied the rest of transformations described in alire#227: no top-level
[genera] table, name/version keys, [[depends-on]] array instead of table.