Fix ICX build (openPMD#1690)

Error was:
 /home/runner/work/openPMD-api/openPMD-api/include/openPMD/backend/Container.hpp:262:32:
error: no member named 'm_container' in 'Container<T, T_key,
T_container>'
  262 |         container().swap(other.m_container);

include/openPMD/backend/Container.hpp

@@ -259,7 +259,7 @@ class Container : virtual public Attributable
 
     void swap(Container &other)
     {
-        container().swap(other.m_container);
+        container().swap(other.container());
     }
 
     mapped_type &at(key_type const &key)