Bump up rust version to 1.70 in the containerfile fo websocket_to_websocket

[JadenFurtado]

In the containerfile of websockt_to_websocket,

FROM docker.io/library/rust:1.66

COPY . /usr/src/websocket-to-websocket

WORKDIR /usr/src/websocket-to-websocket
RUN \
  --mount=type=cache,dst=/root/.cargo \
  --mount=type=cache,dst=/usr/src/websocket-to-websocket/target \
  cargo install --path .

WORKDIR /srv
CMD [ "websocket-to-websocket" ]

The current version of rust is set to 1.66. However, this breaks tokio which requires at least version 1.70 of rustc to compile

To fix this issue, change the version to 1.70