chore(deps): update dependency pixelmatch to v5

Author: renovate-bot

package.json

@@ -63,7 +63,7 @@
     "memory-fs": "^0.4.1",
     "mocha": "^4",
     "mocketeer": "^0.3.0",
-    "pixelmatch": "^4.0.2",
+    "pixelmatch": "^5.0.0",
     "pngjs": "^3.3.0",
     "serve": "^10.1.2"
   },