fix(spinner): remove unused member in model

spinner/spinner.go

@@ -72,7 +72,6 @@ var (
 // Model contains the state for the spinner. Use NewModel to create new models
 // rather than using Model as a struct literal.
 type Model struct {
-
 	// Spinner settings to use. See type Spinner.
 	Spinner Spinner
 
@@ -84,7 +83,6 @@ type Model struct {
 	Style lipgloss.Style
 
 	frame int
-	startTime time.Time
 	id    int
 	tag   int
 }