make medusa-dev-cli compatible with yarn 2/3 (#1765)

packages/medusa-dev-cli/package.json

@@ -16,6 +16,7 @@
     "fs-extra": "^9.0.1",
     "got": "^10.7.0",
     "is-absolute": "^1.0.0",
+    "jest": "^25.5.2",
     "lodash": "^4.17.21",
     "signal-exit": "^3.0.3",
     "verdaccio": "^4.10.0",
@@ -39,10 +40,10 @@
     "directory": "packages/medusa-dev-cli"
   },
   "scripts": {
-    "build": "babel src --out-dir dist --ignore \"**/__tests__\"",
     "prepare": "cross-env NODE_ENV=production npm run build",
-    "test": "echo \"Error: no test specified\" && exit 1",
-    "watch": "babel -w src --out-dir dist --ignore \"**/__tests__\""
+    "build": "babel src --out-dir dist",
+    "test": "jest",
+    "watch": "babel -w src --out-dir dist"
   },
   "engines": {
     "node": ">=12.13.0"