tests: fix building of previewengine_unittest

This test started failing to build with Qt 6.8.2 and/or GCC 14 in
Guix:

   error: ‘class QHttpServer’ has no member named ‘listen’
      31 |         server->listen(QHostAddress::LocalHost, 8000);

Adjust to use what the Qt documentation suggests, which is to bind the
server to a distinct QTcpServer instance.

Fixes: #1144
Change-Id: I3308acab793b3cdf74458f8196933bca26b41bb1

extras/data/net.jami.Jami.metainfo.xml

@@ -17,6 +17,9 @@
   </developer>
 
   <releases>
+    <release version="20250718.0" date="2025-07-18">
+      <url type="details">https://git.jami.net/savoirfairelinux/jami-client-qt/-/wikis/Changelog#nightlystable-20250718</url>
+    </release>
     <release version="20250613.0" date="2025-06-13">
       <url type="details">https://git.jami.net/savoirfairelinux/jami-client-qt/-/wikis/Changelog#nightlystable-20250613</url>
     </release>

tests/unittests/previewengine_unittest.cpp

@@ -17,7 +17,8 @@
 
 #include "globaltestenvironment.h"
 
-#include <QtHttpServer/QHttpServer>
+#include <QtHttpServer>
+#include <QTcpServer>
 
 class PreviewEngineFixture : public ::testing::Test
 {
@@ -27,19 +28,27 @@ public:
     void SetUp() override
     {
         server = new QHttpServer();
-        // Setup a server that can return an HTML body.
-        server->listen(QHostAddress::LocalHost, 8000);
+        tcpserver = new QTcpServer();
+
+        // Setup a server that can return an HTML body, which listens
+        // on 127.0.0.1 (localhost) and port 8000.
+        if (!tcpserver->listen(QHostAddress::LocalHost, 8000)
+            || !server->bind(tcpserver)) {
+            qFatal() << "failed to listen:" << tcpserver->errorString();
+        }
     }
 
     // Close unit test context. Called
     // after each unit test ending
     void TearDown() override
     {
+        delete tcpserver;
         delete server;
     }
 
     // An instance of QHttpServer used to create a server.
     QHttpServer* server;
+    QTcpServer* tcpserver;
 };
 
 /*!