Set Cabal version to 3.0 when set notation is used in tested-with field #577
Description
Cabal >= 3.0 allows set notation in the tested-with field, such as
tested-with: GHC == { 8.6.3, 8.4.4, 8.2.2, 8.0.2, 7.10.3, 7.8.4, 7.6.3, 7.4.2 }When we use set notation in the tested-with field in package.yaml, the field is copied to the .cabal file, but the cabal-version is not set to >= 3.0 as needed. This results in the following error when we try to cabal build using the generated cabal file:
unexpected version set syntax used. To use this syntax the package needs to specify at least 'cabal-version: 3.0'. Alternatively, if broader compatibility is important then use a series of single version constraints joined with the || operator: ==8.6.3 || ==8.4.4 || ==8.2.2 || ==8.0.2 || ==7.10.3 || ==7.8.4 || ==7.6.3 || ==7.4.2
20 | tested-with:
21 | GHC == { 8.6.3, 8.4.4, 8.2.2, 8.0.2, 7.10.3, 7.8.4, 7.6.3, 7.4.2 }
| ^ ^