refactor: workspace autostop_schedule -> ttl (#1578)

Co-authored-by: G r e y <grey@coder.com>

agent/usershell/usershell_darwin.go

@@ -3,6 +3,6 @@ package usershell
 import "os"
 
 // Get returns the $SHELL environment variable.
-func Get(username string) (string, error) {
+func Get(_ string) (string, error) {
 	return os.Getenv("SHELL"), nil
 }