fix: forceGlobalSecureRequests break URI schemes other than HTTP

Author: kenjis

system/HTTP/URI.php

@@ -596,7 +596,7 @@ public function __toString(): string
             }
 
             // Check for forced HTTPS
-            if ($config->forceGlobalSecureRequests) {
+            if ($config->forceGlobalSecureRequests && $this->getScheme() === 'http') {
                 $scheme = 'https';
             }
         }

tests/system/HTTP/URITest.php

@@ -985,4 +985,20 @@ public function testCreateURIString()
 
         $this->assertSame($expected, $uri);
     }
+
+    /**
+     * @see https://github.com/codeigniter4/CodeIgniter4/issues/5728
+     */
+    public function testForceGlobalSecureRequestsAndNonHTTPProtocol()
+    {
+        $config                            = new App();
+        $config->forceGlobalSecureRequests = true;
+        $config->baseURL                   = 'https://localhost/';
+        Factories::injectMock('config', 'App', $config);
+
+        $expected = 'ftp://localhost/path/to/test.txt';
+        $uri      = new URI($expected);
+
+        $this->assertSame($expected, (string) $uri);
+    }
 }