Tighten lower bound on lens, since the bigger FieldN classes are used (…

…#145)

linear.cabal

@@ -66,7 +66,7 @@ library
     distributive         >= 0.2.2 && < 1,
     ghc-prim,
     hashable             >= 1.1   && < 1.3,
-    lens                 >= 4     && < 5,
+    lens                 >= 4.15.2 && < 5,
     reflection           >= 1.3.2 && < 3,
     semigroups           >= 0.9   && < 1,
     semigroupoids        >= 5.2.1 && < 5.3,