tools: update tap + mock-fs. Fix broken test

The test suite is currently failing on anything higher than v4

Updating mock-fs fixes this. As tap was quite out of date I have
updated that as well.

After updating the dependencies a test began failing due to
`test.end()` being called more than once. This is fixed

package.json

@@ -19,8 +19,8 @@
     "minimist": "0.0.8"
   },
   "devDependencies": {
-    "tap": "1",
-    "mock-fs": "2 >=2.7.0"
+    "mock-fs": "^3.7.0",
+    "tap": "^5.4.2"
   },
   "bin": "bin/cmd.js",
   "license": "MIT"

test/perm.js

@@ -28,5 +28,4 @@ test('async root perm', function (t) {
         if (err) t.fail(err);
         t.end();
     });
-    t.end();
 });