Update mockttp for a double-slash URL parsing fix

Author: pimterry

package-lock.json

@@ -55,7 +55,7 @@
     "iconv-lite": "^0.4.24",
     "lodash": "^4.17.19",
     "mime-types": "^2.1.27",
-    "mockttp": "^1.0.3",
+    "mockttp": "^1.0.4",
     "node-fetch": "^2.6.1",
     "node-forge": "^0.10.0",
     "node-gsettings-wrapper": "^0.5.0",