RUSTSEC-2021-0052

The following functions in the crate are affected:

## `IdMap::clone_from`

The `clone_from` implementation for `IdMap` drops the values present in the map and then begins cloning values from the other map. If a `.clone()` call pancics, then the afformentioned dropped elements can be freed again.

## `get_or_insert`

`get_or_insert` reserves space for a value, before calling the user provided insertion function `f`. If the function `f` panics then uninitialized or previously freed memory can be dropped.

## `remove_set`

When removing a set of elements, `ptr::drop_in_place` is called on each of the element to be removed. If the `Drop` impl of one of these elements panics then the previously dropped elements can be dropped again.