copilot-verifier: Relax version constraints on what4. Refs #716.

In order to keep Copilot effectively working in the current Haskell
ecosystem, as well as new versions of GHC, we need to extend the
versions of dependencies that Copilot can be installed with. For
example, ogma-extra has seen release 1.12, but copilot-visualizer needs
versions strictly lower than 1.10.

This commit relaxes the version constrains on `what4` for the
`copilot-verifier` package.

Author: ivanperez-keera

copilot-verifier/copilot-verifier.cabal

@@ -62,7 +62,7 @@ common bldflags
     text,
     transformers,
     vector,
-    what4 >= 1.6.1 && < 1.7
+    what4 >= 1.6.1 && < 1.8
 
 library
   import: bldflags