services: Require wpa-supplicant-service for connman-service.

* gnu/services/networking.scm (connman-shepherd-service): Add
  wpa-supplicant among list of requirements.

gnu/services/networking.scm

@@ -714,7 +714,7 @@ (define (connman-shepherd-service connman)
   (list (shepherd-service
          (documentation "Run Connman")
          (provision '(networking))
-         (requirement '(user-processes dbus-system loopback))
+         (requirement '(user-processes dbus-system loopback wpa-supplicant))
          (start #~(make-forkexec-constructor
                    (list (string-append #$connman
                                         "/sbin/connmand")