fix: Build server script tsconfig (#81)

What
- Update the build:server script to use the correct tsconfig file

package.json

@@ -15,7 +15,7 @@
   "scripts": {
     "clean": "cross-env ./node_modules/.bin/rimraf dist",
     "build": "cross-env npm run clean && npm run build:server && npm run build:admin",
-    "build:server": "cross-env npm run clean && tsc -p tsconfig.json",
+    "build:server": "cross-env npm run clean && tsc -p tsconfig.server.json",
     "build:admin": "cross-env medusa-admin build",
     "watch": "cross-env tsc --watch",
     "test": "cross-env jest",