fix: Add zen-observable to adapter-memory

Author: relekang

packages/adapter-memory/package.json

@@ -14,7 +14,9 @@
     "micro-analytics",
     "adapter"
   ],
-  "dependencies": {},
+  "dependencies": {
+    "zen-observable": "^0.5.1"
+  },
   "devDependencies": {
     "micro-analytics-adapter-utils": "^0.0.1"
   }

packages/adapter-memory/yarn.lock

@@ -11,3 +11,7 @@ micro-analytics-adapter-utils@^0.0.1:
   resolved "https://registry.yarnpkg.com/micro-analytics-adapter-utils/-/micro-analytics-adapter-utils-0.0.1.tgz#e953f4795980da1fa758083004fd43cc975ceea6"
   dependencies:
     escape-regex "^1.0.7"
+
+zen-observable@^0.5.1:
+  version "0.5.1"
+  resolved "https://registry.yarnpkg.com/zen-observable/-/zen-observable-0.5.1.tgz#a2a57908a276b569504f42fdf2fa2f643bc02d72"