fixed concurrent access to single db connection

app/sda-workflow/src/0_scheduler/Scheduler.hpp

@@ -127,7 +127,10 @@ public:
             for(const auto & job: jobsToRun) {
                 executor(job);
             }
-            std::ranges::for_each(this->listener,[this](auto && o){o(*this);});
+            {
+                std::lock_guard lock {this->mutex};
+                std::ranges::for_each(this->listener,[this](auto && o){o(*this);});
+            }
             std::this_thread::sleep_for(std::chrono::milliseconds(100));
         }
         std::ranges::for_each(this->listener,[this](auto && o){o(*this);});