copilot-theorem: Relax version constraint on what4. Refs #611.

what4 has seen a new release 1.7, but copilot-theorem needs versions
strictly lower than 1.7. This version is API-compatible for all features
used by copilot-theorem.

Author: ivanperez-keera

copilot-theorem/copilot-theorem.cabal

@@ -61,7 +61,7 @@ library
                           , random                >= 1.1 && < 1.3
                           , transformers          >= 0.5 && < 0.7
                           , xml                   >= 1.3 && < 1.4
-                          , what4                 >= 1.3 && < 1.7
+                          , what4                 >= 1.3 && < 1.8
 
                           , copilot-core          >= 4.4 && < 4.5
                           , copilot-prettyprinter >= 4.4 && < 4.5