added Do method for raw query by single conn from pool.Conn()

do.go

@@ -0,0 +1,9 @@
+package redis
+
+import "context"
+
+func (c cmdable) Do(ctx context.Context, args ...interface{}) *Cmd {
+	cmd := NewCmd(ctx, args)
+	_ = c(ctx, cmd)
+	return cmd
+}

do_test.go

@@ -0,0 +1,27 @@
+package redis_test
+
+import (
+	. "github.com/bsm/ginkgo/v2"
+	. "github.com/bsm/gomega"
+
+	"github.com/redis/go-redis/v9"
+)
+
+var _ = Describe("Do cmdble", func() {
+	var client *redis.Client
+
+	BeforeEach(func() {
+		client = redis.NewClient(redisOptions())
+		Expect(client.FlushDB(ctx).Err()).NotTo(HaveOccurred())
+	})
+
+	AfterEach(func() {
+		client.Close()
+	})
+
+	It("should pong with Do cmd", func() {
+		result := client.Conn().Do(ctx, "PING")
+		Expect(result.Result()).To(Equal("PONG"))
+		Expect(result.Err()).NotTo(HaveOccurred())
+	})
+})