Added signin route in backend

backend/src/repositories/user.repo.js

@@ -13,4 +13,14 @@ export const createUser = async (username, email, password) => {
     catch(err) {
         throw err
     }
+}
+
+export async function findUserByEmail(email) {
+    try{
+        const user = await UserModel.findOne({email});
+        return user;
+    }
+    catch(err){
+        throw err;
+    }
 }