Update test utils to cater for GHC 8.6.5

Author: alanz

test/utils/TestUtils.hs

@@ -133,7 +133,9 @@ ghcVersion = GHCPre84
 
 stackYaml :: FilePath
 stackYaml =
-#if (defined(MIN_VERSION_GLASGOW_HASKELL) && (MIN_VERSION_GLASGOW_HASKELL(8,6,4,0)))
+#if (defined(MIN_VERSION_GLASGOW_HASKELL) && (MIN_VERSION_GLASGOW_HASKELL(8,6,5,0)))
+  "stack.yaml"
+#elif (defined(MIN_VERSION_GLASGOW_HASKELL) && (MIN_VERSION_GLASGOW_HASKELL(8,6,4,0)))
   "stack-8.6.4.yaml"
 #elif (defined(MIN_VERSION_GLASGOW_HASKELL) && (MIN_VERSION_GLASGOW_HASKELL(8,6,3,0)))
   "stack-8.6.3.yaml"