Added skeleton code for register endpoint (#2)

Reviewed-on: phoenix/textsender-auth#2
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

migrations/schema.sql

@@ -0,0 +1,11 @@
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+
+DROP TABLE IF EXISTS users CASCADE;
+
+CREATE TABLE users (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    phone_number TEXT NOT NULL,
+    username TEXT NOT NULL,
+    password TEXT NOT NULL
+);
+