remove multiply clear definition

include/pocketpy/vector.h

@@ -259,8 +259,6 @@ namespace pkpy {
 
         reverse_iterator rbegin() { return reverse_iterator(end()); }
 
-        void clear() { while (m_size > 0) pop_back(); }
-
         const_reverse_iterator rbegin() const {
             return const_reverse_iterator(end());
         }