Install rust toolchain

Author: carlcsaposs-canonical

spread.yaml

@@ -100,8 +100,15 @@ backends:
       - self-hosted-linux-s390x-noble-edge:
           username: ubuntu
           environment:
-            # pkg-config needed to build cryptography to install poetry
-            CONCIERGE_EXTRA_DEBS: pipx,pkg-config
+            # Several python packages (e.g. cryptography, bcrypt) do not have s390x builds on PyPI,
+            # so they must be built from source. `pkg-config` and rust toolchain needed
+            # (These packages are being built when installing poetry or integration test Python
+            # dependencies)
+            CONCIERGE_EXTRA_DEBS: pipx,pkg-config,rustup
+          # TODO add renovate comment for rust version
+          prepare: |
+            rustup set profile minimal
+            rustup default 1.88.0
           variants:
             - -juju29_ubuntu22