[core] Switch to ankerl::unordered_dense

Signed-off-by: x7z4w <x7z4w@noreply.codeberg.org>

libs/base/clustering_map.hpp

@@ -4,10 +4,11 @@
 
 #include <cstddef>
 #include <iterator>
-#include <unordered_map>
 #include <utility>
 #include <vector>
 
+#include "3party/ankerl/unordered_dense.h"
+
 namespace base
 {
 // Maps keys to lists of values, but allows to combine keys into
@@ -155,6 +156,6 @@ private:
     cv.shrink_to_fit();
   }
 
-  std::unordered_map<Key, Entry, Hash> m_table;
+  ankerl::unordered_dense::map<Key, Entry, Hash> m_table;
 };
 }  // namespace base