fix: upgrade mpath -> 0.8.4 re: mongoosejs/mpath#13

Author: vkarpov15

package.json

@@ -22,7 +22,7 @@
     "bson": "^4.2.2",
     "kareem": "2.3.2",
     "mongodb": "4.1.1",
-    "mpath": "0.8.3",
+    "mpath": "0.8.4",
     "mquery": "4.0.0",
     "ms": "2.1.2",
     "regexp-clone": "1.0.0",