Fix fmt.Sprintf time to float issue

There used to be errors such as:
fmt.Sprintf format %.1f has arg note.BeginTime of wrong type time.Time

This commit fixes it by converting the time into unix nano seconds
then converts it into seconds.

internal/observation/observation.go

@@ -93,9 +93,12 @@ func WriteNotesTable(settings *conf.Settings, notes []datastore.Note, filename s
 			continue // Skip the current iteration as the note doesn't meet the threshold
 		}
 
+		beginTime := float64(note.BeginTime.UnixNano()) / 1e9
+		endTime := float64(note.EndTime.UnixNano()) / 1e9
+
 		// Prepare the line for notes above the threshold
 		line := fmt.Sprintf("%d\tSpectrogram 1\t1\t%s\t%.1f\t%.1f\t0\t15000\t%s\t%s\t%.4f\n",
-			i+1, note.InputFile, note.BeginTime, note.EndTime, note.SpeciesCode, note.CommonName, note.Confidence)
+			i+1, note.InputFile, beginTime, endTime, note.SpeciesCode, note.CommonName, note.Confidence)
 
 		// Attempt to write the note
 		if _, err = w.Write([]byte(line)); err != nil {
@@ -154,8 +157,11 @@ func WriteNotesCsv(settings *conf.Settings, notes []datastore.Note, filename str
 			continue // Skip the current iteration as the note doesn't meet the threshold
 		}
 
+		beginTime := float64(note.BeginTime.UnixNano()) / 1e9
+		endTime := float64(note.EndTime.UnixNano()) / 1e9
+
 		line := fmt.Sprintf("%f,%f,%s,%s,%.4f\n",
-			note.BeginTime, note.EndTime, note.ScientificName, note.CommonName, note.Confidence)
+			beginTime, endTime, note.ScientificName, note.CommonName, note.Confidence)
 
 		if _, err = w.Write([]byte(line)); err != nil {
 			// Break out of the loop at the first sign of an error