support building with base-4.18

[joeyh]

feed depends on base < 4.18, but ghc-9.6.2 has base-4.18. Probably this dependency can simply be relaxed.

[sternenseemann]

Building with 4.18 works fine, so all that should be required would be a bound revision!

[Bodigrim]

As a Hackage trustee I made a revision: https://hackage.haskell.org/package/feed-1.3.2.1/revisions/

[sternenseemann]

@Bodigrim why was the base-compat bound lowered? I've been able to build feed-1.3.2.1 with GHC 9.6 and base-compat-0.13.1 seemingly fine (the latter is in Stackage LTS 22).

[Bodigrim]

@sternenseemann there was a brief period of time when Hackage revisions had to specify all upper bounds, so I had to put some for base-compat. Relaxed now in https://hackage.haskell.org/package/feed-1.3.2.1/revisions/