Minor: Update Rust version (apache#3048)

* Minor: Update Rust version

* Bump to 1.73

BUILD.md

@@ -17,7 +17,7 @@ The following packages must be installed before Avro can be built:
    Math::BigInt, JSON::MaybeXS, Try::Tiny, Regexp::Common, Encode,
    Object::Tiny, Compress::ZLib, Error::Simple, Test::More,
    Test::Exception, Test::Pod
- - Rust: rustc and Cargo 1.65.0 or greater
+ - Rust: rustc and Cargo 1.73.0 or greater
  - Apache Ant 1.7
  - md5sum, sha1sum, used by top-level dist target