rel8.cabal: Allow base ^>=4.21 (GHC 9.12)

Author: JackKelly-Bellroy

rel8.cabal

@@ -21,7 +21,7 @@ library
   build-depends:
       aeson
     , attoparsec
-    , base ^>= 4.16 || ^>= 4.17 || ^>= 4.18 || ^>= 4.19 || ^>= 4.20
+    , base ^>= 4.16 || ^>= 4.17 || ^>= 4.18 || ^>= 4.19 || ^>= 4.20 || ^>= 4.21
     , base16 >= 1.0
     , base-compat ^>= 0.11 || ^>= 0.12 || ^>= 0.13 || ^>= 0.14
     , bifunctors