🚨 Fix lint warning

Type asserting to convert an interface (error) to the concrete type is
unnecessary when using errors.As. The documentation states the
following:

> As finds the first error in err's chain that matches target, and if
> one is found, sets target to that error value and returns true.
> Otherwise, it returns false.

Remove the assertion as the error was already stored in the variable.
The path stored in the error can be directly accessed.

internal/shell/shell.go

@@ -31,8 +31,6 @@ func Run(w io.Writer, command string, args []string) error {
 			return fmt.Errorf("unable to copy commit output: %w", err)
 		}
 
-		//nolint:errorlint
-		pathError = err.(*fs.PathError)
 		if pathError.Path != "/dev/ptmx" {
 			return fmt.Errorf("unable to copy commit output: %v: %w", pathError.Path, pathError.Err)
 		}