cabal2nix: add upper bound on Cabal

cabal2nix often breaks on Cabal updates, so it seems sensible to
add an upper bound (which we can always relax via revisions). This
seems like a better approach going forward compared to going back
and adding the constraint.

Author: sternenseemann

cabal2nix/cabal2nix.cabal

@@ -52,7 +52,7 @@ library
   build-depends:      base                 > 4.11 && <5
                     -- When changing the Cabal version, ensure that it builds
                     -- with all installation methods mentioned in the README!
-                    , Cabal                >= 3.0
+                    , Cabal                >= 3.0 && < 3.18
                     , aeson                > 1
                     , ansi-terminal
                     , bytestring