doc: reflect MSRV change

Author: FreezyLemon

README.md

@@ -50,7 +50,7 @@ If you'd like to modify where the data is downloaded, you can use the environmen
 
 ## Minimum supported Rust version (MSRV)
 
-This crate requires a Rust version of 1.66.0 or higher. Increases in MSRV will be considered a semver non-breaking API change and require a version increase (PATCH until 1.0.0, MINOR after 1.0.0).
+This crate requires a Rust version of 1.61.0 or higher. Increases in MSRV will be considered a semver non-breaking API change and require a version increase (PATCH until 1.0.0, MINOR after 1.0.0).
 
 ## Contributing