Update FirefoxConfig.cs

Author: rosolko

WebDriverManager/DriverConfigs/Impl/FirefoxConfig.cs

@@ -43,7 +43,7 @@ public virtual string GetLatestVersion()
                 var htmlCode = client.DownloadString("https://github.com/mozilla/geckodriver/releases");
                 var parser = new HtmlParser();
                 var document = parser.ParseDocument(htmlCode);
-                var version = document.QuerySelectorAll(".Link--primary")
+                var version = document.QuerySelectorAll("[class='Link--primary']")
                     .Select(element => element.TextContent)
                     .FirstOrDefault()
                     ?.Replace("v", "");