Force rerun of version splice when commit or cabal file changes

[guaraqe]

I has looking at the definition of tGitInfo, and it seems to use addDependentFile to track whether the splice needs to be recompiled or not.

Maybe this trick could be used here too, and also the cabal file added to the dependent files, so that no extra effort is needed to make sure versions are in-line with the compiled binary.

[istathar]

This is such a good idea! I knew [something like this mechanism] was triggered when you included a file verbatim, for example, but it had not occurred to me that the mechanism was available and could be used here.