fix(os/gtime): fix gtime.Value() when time only, add time only example

[niluan304]

add only time case for func (t *Time) Value() (driver.Value, error):

// Value is the interface providing the Value method for package database/sql/driver
// for retrieving value from golang variable to database.
func (t *Time) Value() (driver.Value, error) {
	if t == nil {
		return nil, nil
	}
	if t.IsZero() {
		return nil, nil
	}

	if t.Year() == 0 {
		// Only time.
		return t.Format("15:04:05"), nil
	}

	return t.Time, nil
}

the pr can Fixes #2012

add some time only example.

[cyjaysong]

看看我这种方案如何
#3712

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Let’s see how my plan goes
#3712

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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