Bug#1142931: ghdl: build-depends on gcc-14

Source: ghdl
Version: 6.0.0+dfsg3-1
Severity: serious

Your package build-depends on GCC 14, which won't be shipped in
forky. Please use the default GCC if possible (currently 15) instead
of hardcoding a specific version, or alternatively, use a newer version
(15 or 16).

Cheers,
Emilio