Increase the capacity to at least a certain amount.

This increases the capacity() to a value that is greater than or equal to new_capacity. If new_capacity > capacity(), new memory is allocated. Otherwise, the call has no effect. The number of elements and therefore the size() of the container is not changed.

If new memory is allocated, all iterators including any past-the-end iterators, and all references to the elements are invalidated. Otherwise, no iterators or references are invalidated.

At most, linear in size().

Strong guarantee. Calls to memory_resource::allocate may throw.