Bump spec up to allow ctools 4.

Gave it a run through here, and seemed to work fine; however, ctools'
project page still seems to suggest the 3 major version should be
preferred... but let's allow 4, if people are using or want to test it
out?

composer.json

@@ -29,7 +29,7 @@
     "drupal/flysystem" : "^2.0@alpha",
     "islandora/crayfish-commons": "^2",
     "drupal/file_replace": "^1.1",
-    "drupal/ctools": "^3.8"
+    "drupal/ctools": "^3.8 || ^4"
   },
   "require-dev": {
     "phpunit/phpunit": "^6",