Raise MSRV to 1.46.0 due to dependencies

Author: eldruin

README.md

@@ -53,7 +53,7 @@ cross-compile.  See https://github.com/japaric/rust-cross for pointers.
 
 ## Minimum Supported Rust Version (MSRV)
 
-This crate is guaranteed to compile on stable Rust 1.32.0 and up. It *might*
+This crate is guaranteed to compile on stable Rust 1.46.0 and up. It *might*
 compile with older versions but that may change in any new patch release.
 
 ## License