Add timestamp to migrations.run_at.

src/main/nim/db_migrate.nim

@@ -20,7 +20,7 @@ WHERE table_name = 'migrations';""")
 CREATE TABLE IF NOT EXISTS migrations (
   id SERIAL PRIMARY KEY,
   name VARCHAR NOT NULL,
-  run_at TIMESTAMP NOT NULL DEFAULT NOW())"""))
+  run_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW())"""))
 
 proc rollbackWithErr (pgConn: DbConn, errMsg: string): void =
   pgConn.exec(sql"ROLLBACK")