Update improvement count

Author: Mark-Simulacrum

triage/2021-04-06.md

@@ -10,7 +10,7 @@ Revision range: [4896450e7e0a522486b4d3a8d360ac4e1d2072a0..d32238532138485c80db4
 
 [memory usage improvements]: https://perf.rust-lang.org/?start=4896450e7e0a522486b4d3a8d360ac4e1d2072a0&end=d32238532138485c80db4f2cd596372bce214e00&absolute=false&stat=max-rss
 
-1 Regressions, 3 Improvements, 0 Mixed
+1 Regressions, 4 Improvements, 0 Mixed
 
 #### Regressions