Create DB migrations for users table

migrations/2024-01-17-032155_create_users_table/down.sql

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+DROP TABLE users;

migrations/2024-01-17-032155_create_users_table/up.sql

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+CREATE TABLE users (
+    id SERIAL PRIMARY KEY UNIQUE NOT NULL,
+    username VARCHAR UNIQUE NOT NULL,
+    email VARCHAR UNIQUE NOT NULL,
+    password VARCHAR NOT NULL,
+    created_at TIMESTAMP NOT NULL DEFAULT NOW()
+);