Downgrade edition to not have problems with MSRV in dependent crates.

Author: rklaehn

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "sorted-index-buffer"
 version = "0.1.0"
-edition = "2024"
+edition = "2021"
 readme = "README.md"
 description = "array based sorted map with u64 keys"
 license = "MIT OR Apache-2.0"