amqprs

prepare release v2.1.2. prepare v2.1.2

Update min FRAME_MAX to match that of RabbitMQ 4.1.x (#169)

fix: rustls aws-lc-rs/ring compatibility by disabling default features (#167)

Update 3rd deps, fix tls tests, step up MSRV to 1.71 (#148)

add failure detection in basic_pub_sub example to prevent regression (#165)