fix lambda captures and rebump to v0.5.5

- fixed importing cmdr11(-cxx) via cmake ExternalProject_Add
- fixed for c++20

libs/cmdr11/include/cmdr11/cmdr_app_inl.h

@@ -151,19 +151,19 @@ namespace cmdr {
   }
 
   inline void app::internal_register_actions() {
-    _internal_actions.emplace(opt::Action::RequestHelpScreen, [=](opt::types::parsing_context &pc, int, char *[]) -> int {
-      print_usages(&pc.last_matched_cmd());
+    _internal_actions.emplace(opt::Action::RequestHelpScreen, [this](opt::types::parsing_context &pc, int, char *[]) -> int {
+      this->print_usages(&pc.last_matched_cmd());
       return 0;
     });
-    _internal_actions.emplace(opt::Action::RequestVersionsScreen, [=](opt::types::parsing_context &, int, char *[]) -> int {
+    _internal_actions.emplace(opt::Action::RequestVersionsScreen, [this](opt::types::parsing_context &, int, char *[]) -> int {
       auto vs     = this->_version;
       auto &vsvar = this->get_for_cli("version-sim");
       if (!vsvar.empty()) vs = vsvar.as<const_chars>();
       if (vs.empty()) vs = this->_version;
       std::cout << vs << '\n';
       return 0;
     });
-    _internal_actions.emplace(opt::Action::RequestBuildInfoScreen, [=](opt::types::parsing_context &, int, char *[]) -> int {
+    _internal_actions.emplace(opt::Action::RequestBuildInfoScreen, [](opt::types::parsing_context &, int, char *[]) -> int {
       std::tm t{};
       std::istringstream tsi(__TIMESTAMP__);
       // tsi.imbue(std::locale("de_DE.utf-8"));