secrets/create: remove pipe check and allow interactive stdin

Previously, `secret create` required stdin to be a pipe when using `-`,
blocking interactive stdin forcing users to use insecure patterns like
`echo "secret" | podman secret create <name>`.

Remove the pipe check to allow interactive stdin.

Closes #18591, #27879

Signed-off-by: Danish Prakash <contact@danishpraka.sh>

cmd/podman/secrets/create.go

@@ -82,13 +82,6 @@ func create(_ *cobra.Command, args []string) error {
 		}
 		reader = strings.NewReader(envValue)
 	case path == "-" || path == "/dev/stdin":
-		stat, err := os.Stdin.Stat()
-		if err != nil {
-			return err
-		}
-		if (stat.Mode() & os.ModeNamedPipe) == 0 {
-			return errors.New("if `-` is used, data must be passed into stdin")
-		}
 		reader = os.Stdin
 	default:
 		file, err := os.Open(path)