History of Pool::evict 4 changes

In crates/flow/src/cache.rs, lines 325–355 on v0.3.1. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 325,355:crates/flow/src/cache.rs.