fix: redshift driver issue (#567)

Co-authored-by: Mike Fridman <mf192@icloud.com>

cmd/goose/main.go

@@ -125,7 +125,7 @@ func main() {
 	case "sqlite3":
 		//  Internally uses the CGo-free port of SQLite: modernc.org/sqlite
 		driver = "sqlite"
-	case "postgres":
+	case "postgres", "redshift":
 		driver = "pgx"
 	}
 	db, err := goose.OpenDBWithDriver(driver, normalizeDBString(driver, dbstring, *certfile, *sslcert, *sslkey))

db.go

@@ -15,8 +15,6 @@ func OpenDBWithDriver(driver string, dbstring string) (*sql.DB, error) {
 	switch driver {
 	case "mssql":
 		driver = "sqlserver"
-	case "redshift":
-		driver = "postgres"
 	case "tidb":
 		driver = "mysql"
 	}