Appease clippy in Rust 1.70 (#4365)

## Issue Addressed

NA

## Proposed Changes

Fixes some new clippy lints raised after updating to Rust 1.70.

## Additional Info

NA

common/lru_cache/src/time.rs

@@ -1,4 +1,4 @@
-///! This implements a time-based LRU cache for fast checking of duplicates
+//! This implements a time-based LRU cache for fast checking of duplicates
 use fnv::FnvHashSet;
 use std::collections::VecDeque;
 use std::time::{Duration, Instant};