Fix wrong total duration caused by divided by zero conversion

[Methapon2001]

fixes #601

I came into this issue when trying to create music player as my learning project and notice that total duration is not quite right as the music ended before total duration reached.

The cause seems to be related to 0 division and convert to u32.

I also added test case for the conversion, I'm not sure if it is needed.
Any feedback is welcome.

Code:

        let total_duration = track
            .codec_params
            .time_base
            .zip(track.codec_params.n_frames)
            .map(|(time_base, n_frames)| time_base.calc_time(n_frames));

        total_duration.map(|time| {
            let hours = time.seconds / (60 * 60);
            let mins = (time.seconds % (60 * 60)) / 60;
            let secs = f64::from((time.seconds % 60) as u32) + time.frac;

            println!("Time: {}", format!("{}:{:0>2}:{:0>6.3}", hours, mins, secs))
        });

        total_duration.map(|Time { seconds, frac }| {
            let dur = Duration::new(seconds, (1f64 / frac) as u32).as_secs();

            let hours = dur / (60 * 60);
            let mins = dur / 60;
            let secs = dur % 60;

            println!(
                "Duration: {}",
                format!("{}:{:0>2}:{:0>2}", hours, mins, secs)
            );
        });

        total_duration.map(|Time { seconds, frac }| {
            let dur =
                Duration::new(seconds, if frac > 0.0 { (1f64 / frac) as u32 } else { 0 }).as_secs();

            let hours = dur / (60 * 60);
            let mins = dur / 60;
            let secs = dur % 60;

            println!(
                "Fixed Divided by 0 Duration: {}",
                format!("{}:{:0>2}:{:0>2}", hours, mins, secs)
            );
        });

Result:

Time: 0:00:07.000
Duration: 0:00:11
Fixed Divided by 0 Duration: 0:00:07