bump `tap` and `nyc`

package.json

@@ -173,14 +173,14 @@
     "inquirer": "^1.0.2",
     "lolex": "^1.4.0",
     "mkdirp": "^0.5.1",
-    "nyc": "^7.1.0",
+    "nyc": "^8.3.0",
     "pify": "^2.3.0",
     "proxyquire": "^1.7.4",
     "rimraf": "^2.5.0",
     "signal-exit": "^3.0.0",
     "sinon": "^1.17.2",
     "source-map-fixtures": "^2.1.0",
-    "tap": "^6.3.0",
+    "tap": "^7.1.2",
     "touch": "^1.0.0",
     "xo": "*",
     "zen-observable": "^0.3.0"