Fix typo in README (#735)

Co-authored-by: Simon Gasse <[email protected]>

Author: sgasse

README.md

@@ -369,7 +369,7 @@ Commits to main are run automatically on [evergreen](https://evergreen.mongodb.c
 
 ## Minimum supported Rust version (MSRV)
 
-The MSRV for this crate is currently 1.57.0. This will be rarely be increased, and if it ever is,
+The MSRV for this crate is currently 1.57.0. This will rarely be increased, and if it ever is,
 it will only happen in a minor or major version release.
 
 ## License