Fix absl/strings/str_cat includes in Ecclesia redfish.

PiperOrigin-RevId: 615067805

Author: ecclesia-robot

ecclesia/lib/redfish/interface.h

@@ -34,6 +34,7 @@
 #include "absl/log/log.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
 #include "absl/time/time.h"