gnu: restinio: Update to 0.6.18-0.eda471e and enable tests.

* gnu/packages/networking.scm (restinio): Update to 0.6.18-0.eda471e.
[version]: Use git-version.
[arguments]: Enable tests, removing #:tests? argument.

gnu/packages/networking.scm

@@ -3709,24 +3709,25 @@ (define-public restbed
     (license license:agpl3+)))
 
 (define-public restinio
+  ;; Temporarily use an unreleased commit, which includes fixes to be able to
+  ;; run the test suite in the resolver-less Guix build environment.
+  (let ((revision "0")
+        (commit "eda471ec3a2815965ca02ec93a1124a342b7601d"))
     (package
       (name "restinio")
-    (version "0.6.17")
+      (version (git-version "0.6.18" revision commit))
       (source (origin
                 (method git-fetch)
                 (uri (git-reference
                       (url "https://github.com/Stiffstream/restinio")
-                    (commit (string-append "v." version))))
+                      (commit commit)))
                 (file-name (git-file-name name version))
                 (sha256
                  (base32
-                "1jpvfa2sjkihbkcc1q6c9zb1vry9mkkhbz2jrl831bqslpq9la3p"))))
+                  "0f4w7714r0ic7csgxydw2vzfh35ssk34pns9jycmc08dzc3r7whb"))))
       (build-system cmake-build-system)
       (arguments
        (list
-      ;; Multiple tests fail to run in the build container due to host name
-      ;; resolution (see: https://github.com/Stiffstream/restinio/issues/172).
-      #:tests? #f
         #:configure-flags #~(list "-DRESTINIO_FIND_DEPS=ON"
                                   "-DRESTINIO_INSTALL=ON"
                                   "-DRESTINIO_TEST=ON"
@@ -3757,7 +3758,7 @@ (define-public restinio
       (description "RESTinio is a header-only C++14 library that gives you an embedded
 HTTP/Websocket server.  It is based on standalone version of ASIO
 and targeted primarily for asynchronous processing of HTTP-requests.")
-    (license license:bsd-3)))
+      (license license:bsd-3))))
 
 (define-public opendht
   (package