Bump rust from 1.80-bullseye to 1.81-bullseye in /images/prow-tests

Bumps rust from 1.80-bullseye to 1.81-bullseye.

---
updated-dependencies:
- dependency-name: rust
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

images/prow-tests/Dockerfile

@@ -265,7 +265,7 @@ RUN git clone https://github.com/kubernetes/kops /tmp/kops && cd /tmp/kops/tests
     go install .
 
 ############################################################
-FROM rust:1.80-bullseye AS external-rust-gets
+FROM rust:1.81-bullseye AS external-rust-gets
 
 ARG CODESIGN_VERSION=0.22.0
 # change this when a new version with https://github.com/indygreg/apple-platform-rs/pull/20 is cut