chore(deps): update rust docker tag to v1.91

Author: renovate[bot]

Dockerfile

@@ -5,7 +5,7 @@ COPY ./frontend /app
 RUN yarn install && yarn build
 
 # Now build the backend with the frontend files embedded
-FROM rust:1.89-slim-bookworm as chef
+FROM rust:1.91-slim-bookworm as chef
 RUN apt-get update -y && \
     apt-get install --no-install-recommends -y pkg-config make g++ libssl-dev curl jq && \
     rustup target add x86_64-unknown-linux-gnu && \