fix(medusa-js): missing devDependency was failing repo build task (#2804)

### What

Explicitly declare `@medusajs/medusa` as a devDependency for `@medusajs/medusa-js` client package.

### Why

With our latest version upgrade of `turbo`, peerDependencies aren't taken into account in the build graph. The recommendation is to also explicitly declare them in devDependencies.

### Test

* Run `yarn build --graph`
* Expect to see medusa-js having a dependency on medusa
```
"[root] @medusajs/medusa-js#build" -> "[root] @medusajs/medusa#build"
```

packages/medusa-js/package.json

@@ -32,6 +32,7 @@
     "url": "https://github.com/medusajs/medusa/issues"
   },
   "devDependencies": {
+    "@medusajs/medusa": "^1.7.0",
     "@types/jest": "^26.0.19",
     "cross-env": "^7.0.3",
     "jest": "^26.6.3",