fix: move multer to dependencies so it is installed in production

backend/package.json

@@ -15,7 +15,8 @@
     "dotenv": "^16.3.1",
     "sqlite3": "^5.1.6",
     "sqlite": "^4.1.2",
-    "nodemailer": "^6.9.8"
+    "nodemailer": "^6.9.8",
+    "multer": "^1.4.5-lts.1"
   },
   "devDependencies": {
     "@types/express": "^4.17.17",
@@ -23,6 +24,7 @@
     "@types/cors": "^2.8.13",
     "@types/sqlite3": "^3.1.8",
     "@types/nodemailer": "^6.4.12",
+    "@types/multer": "^1.4.7",
     "typescript": "^5.1.6",
     "nodemon": "^3.0.1",
     "ts-node": "^10.9.1"