Removed property tests for MatchersUtil#equals

These might be useful for a function with a more restricted domain. But for
equals, which accepts two of literally anything, the short run was too short
to catch any problems and the long run tended to exceed the CircleCi timeout.

package.json

@@ -37,7 +37,6 @@
     "ejs": "^2.5.5",
     "eslint": "^6.8.0",
     "eslint-plugin-compat": "^3.8.0",
-    "fast-check": "^1.21.0",
     "fast-glob": "^2.2.6",
     "grunt": "^1.0.4",
     "grunt-cli": "^1.3.2",