chore(deps): update dependency testling to v1.7.7

Author: renovate[bot]

package.json

@@ -72,7 +72,7 @@
     "q": "1.5.1",
     "tap-difflet": "0.7.2",
     "tape": "5.9.0",
-    "testling": "1.7.6",
+    "testling": "1.7.7",
     "time-grunt": "2.0.0",
     "xml2js": "0.6.2"
   },