benchmark: update measurement

Commit 43154b2 appears to have slightly
improved the benchmark performance.

Author: yancyribbens

README.md

@@ -95,8 +95,8 @@ A basic performance comparison between implementations using commodity hardware
 
 |implementation|pool size|ns/iter|
 |-------------:|---------|-------|
-|      Rust SRD|    1,000| 22,446|
-|      Rust BnB|    1,000|552,120|
+|      Rust SRD|    1,000| 21,888|
+|      Rust BnB|    1,000|495,910|
 |  C++ Core BnB|    1,000|816,374|
 
 Note: The measurements where recorded using rustc 1.90 stable.  Expect worse performance with MSRV.