Allow base 4.16 and Cabal 3.4 in cabal-testsuite

cabal-testsuite/cabal-testsuite.cabal

@@ -26,7 +26,7 @@ common shared
   default-language: Haskell2010
 
   build-depends:
-    , base >= 4.6 && <4.15
+    , base >= 4.6 && <4.16
     -- this needs to match the in-tree lib:Cabal version
     , Cabal == 3.5.0.0
 
@@ -109,5 +109,5 @@ executable setup
 
 custom-setup
   -- we only depend on even stable releases of lib:Cabal
-  setup-depends: Cabal == 2.2.* || == 2.4.* || == 3.0.* || ==3.2.*,
+  setup-depends: Cabal == 2.2.* || == 2.4.* || == 3.0.* || ==3.2.* || ==3.4.*,
                  base, filepath, directory

cabal.project.validate.libonly

@@ -19,3 +19,6 @@ package Cabal
   ghc-options: -Werror -fno-ignore-asserts
 package cabal-testsuite
   ghc-options: -Werror -fno-ignore-asserts
+
+-- https://github.com/haskell-hvr/cryptohash-sha256/issues/12
+allow-newer: cryptohash-sha256:base