LRU v0.6.6 Security Advisory

[ChosunOne]

In the rust package, lru version 0.6.6 has a security vulnerability.
See crate issue

= ID: RUSTSEC-2021-0130
= Advisory: https://rustsec.org/advisories/RUSTSEC-2021-0130
= Lru crate has use after free vulnerability.

 Lru crate has two functions for getting an iterator. Both iterators give
 references to key and value. Calling specific functions, like pop(), will remove
 and free the value, and but it's still possible to access the reference of value
 which is already dropped causing use after free.

Resolution is to upgrade to version >= 0.7.1