Fix missing std::regex declaration

/run/build/BambuStudio/src/slic3r/GUI/WebViewDialog.cpp: In member function ‘void Slic3r::GUI::WebViewPanel::SetMakerworldPageLoginStatus(bool, wxString)’:
/run/build/BambuStudio/src/slic3r/GUI/WebViewDialog.cpp:818:10: error: ‘regex’ is not a member of ‘std’; did you mean ‘boost::regex’?
  818 |     std::regex pattern("^https://.*/(.*/){0,1}agree-terms.*");
      |          ^~~~~

src/slic3r/GUI/WebViewDialog.cpp

@@ -7,6 +7,8 @@
 #include "libslic3r_version.h"
 #include "../Utils/Http.hpp"
 
+#include <regex>
+
 #include <boost/property_tree/ptree.hpp>
 #include <boost/property_tree/json_parser.hpp>