update to 0.2.6 release

the cmake needs c++

use cmake to generate more upstream C header files

update C source to 0.29.0.gfm.13

add macro for upstream C version

Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild

refresh to cabal-rpm-2.1.0 with SPDX migration

0.2.4 updates the C library to 0.29.0.gfm.6 which fixes CVE-2022-39209
gfm/security/advisories/GHSA-cgh3-p57x-9q7q
0.2.5 includes support for footnotes
https://hackage.haskell.org/package/cmark-gfm-0.2.5/changelog

Rebuilt for https://fedoraproject.org/wiki/Fedora_37_Mass_Rebuild

rebuild

0.2.3 bundles the C cmark-gfm-0.29.0.gfm.3 library which fixes
gfm/security/advisories/GHSA-mc3g-88wq-6f4x

Rebuilt for https://fedoraproject.org/wiki/Fedora_36_Mass_Rebuild