snap: Add rust to build-packages (#682)

* snap: Add rust to build-packages

When building the snap on s390x some Python modules need to compile
their extensions (rust based), this is not needed on amd64 since pypi
has compiled packages available.

This change add rustc, cargo and pkg-config to the list of
build-packages in the snapcraft.yaml definition.

* Migrate gh action actions/upload-artifact@v4

* Migration gh action actions/download-artifact@v4

.github/workflows/tests.yml

@@ -36,7 +36,7 @@ jobs:
       run: git tag v0.0.0
     - uses: snapcore/action-build@v1
       id: snap-build
-    - uses: actions/upload-artifact@v1
+    - uses: actions/upload-artifact@v4
       with:
         name: charm-snap
         path: ${{ steps.snap-build.outputs.snap }}
@@ -67,7 +67,7 @@ jobs:
         repository: juju-solutions/layer-basic
 
     - name: Download built charm snap
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: charm-snap
         path: tests/charm-minimal/charm-snap

snap/snapcraft.yaml

@@ -34,6 +34,9 @@ parts:
       - libffi-dev
       - libpython3.10-dev
       - python3-pip
+      - rustc
+      - cargo
+      - pkg-config
     # Note that we cannot use any -dev type packages here, as that would pull
     # in the libc6 package.  The libc6 package contains absolute symlinks
     # pointing at /, which is not allowed in a core22 classic snap.