- Always ask for SPDX expression, we can "convert" them to old format
- No default license
- Add cabal-version: 3.0 to the list
- cabal-version is asked using CabalSpecVersion type
- seems to fix what #6619 tries to fix:

```
% /code/shared-haskell/cabal/dist-newstyle/build/x86_64-linux/ghc-8.8.3/cabal-install-3.3.0.0/x/cabal/build/cabal/cabal init -l 'FOO AND BAR'
Cannot parse license: FOO AND BAR
CallStack (from HasCallStack):
  error, called at ./Distribution/ReadE.hs:42:24 in Cabal-3.3.0.0-inplace:Distribution.ReadE
```

an error, but it doesn't loop.