omitempty tag does not work for empty time.Time struct field when using HSet

[gh73962]

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Expected Behavior

type MyHash struct { 
    Key1 string `redis:"key1"`;
    Key2 time.Time `redis:"key2,omitempty"` 
}

should be

hset myhash key1 value1

Current Behavior

hset myhash key1 value1 key2 0001-01-01T00:00:00Z

Possible Solution

https://github.com/redis/go-redis/blob/master/commands.go#L142

func isEmptyValue(v reflect.Value) bool {
	switch v.Kind() {
	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
		return v.Len() == 0
	case reflect.Bool:
		return !v.Bool()
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return v.Int() == 0
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		return v.Uint() == 0
	case reflect.Float32, reflect.Float64:
		return v.Float() == 0
	case reflect.Interface, reflect.Pointer:
		return v.IsNil()
++++++++++++++++++++++++++++++++++++++++++++++
        case reflect.Struct:
                return v.IsZero()
++++++++++++++++++++++++++++++++++++++++++++++
	}
	return false
}

Steps to Reproduce

type MyHash struct { 
    Key1 string `redis:"key1"`;
    Key2 time.Time `redis:"key2,omitempty"` 
}

data := MyHash{
     Key1 : "value1",
     Key2 : time.Time{},
}

if err := rdb.HSet(ctx, "key", model1).Err(); err != nil {
	panic(err)
}

Context (Environment)

Detailed Description

omitempty tag does not work for empty time.Time struct field when using HSet

Possible Implementation

If you agree with the proposal I made in the title "Possible Solution," I can proceed to complete this PR.