fix more clang-tidy

Signed-off-by: Martijn Govers <Martijn.Govers@Alliander.com>

Author: mgovers

power_grid_model_c/power_grid_model/include/power_grid_model/optimizer/tap_position_optimizer.hpp

@@ -614,7 +614,7 @@ class RankIteration {
     };
 
   private:
-    std::vector<IntS> iterations_per_rank_{};
+    std::vector<IntS> iterations_per_rank_;
     Idx rank_index_{};
 };