Create table 't1' with id and username columns

Created a new table 't1' with a serial primary key and a username column.

Author: adela-bytebase

migrations-semver/1.0.1_create_t1.sql

@@ -0,0 +1,4 @@
+CREATE TABLE "public"."t1" (
+    "id" serial PRIMARY KEY,
+    "username" text
+);