Unsupported cabal-version 3.12

Cabal versions 3.12 and above, when specified in the `cabal-version: ` field of `haskell-template.cabal`, give the following build error:
```
Unsupported cabal-version 3.12. See https://github.com/haskell/cabal/issues/4899.
```

Versions up to and including 3.8 work fine, but there seems to be an issue with the two newest versions (3.12 and 3.14)
