Remove charmcraft workaround and build on all archs

Change-Id: I0ba367e4bb181aee76621b3ae3a38dade3b2e8e1

charmcraft.yaml

@@ -7,8 +7,7 @@ parts:
     charm-python-packages:
       # NOTE(lourot): see
       # * https://github.com/canonical/charmcraft/issues/551
-      # * https://github.com/canonical/charmcraft/issues/632
-      - setuptools < 58
+      - setuptools
     build-packages:
       - git
 
@@ -21,7 +20,16 @@ parts:
       update-ca-certificates
 
 bases:
-  - name: ubuntu
-    channel: "20.04"
-    architectures:
-      - amd64
+  - build-on:
+      - name: ubuntu
+        channel: "20.04"
+        architectures:
+          - amd64
+          - s390x
+          - ppc64el
+          - arm64
+    run-on:
+      - name: ubuntu
+        channel: "20.04"
+      - name: ubuntu
+        channel: "21.10"

tests/README.md

@@ -10,7 +10,6 @@ Run the smoke tests with:
 ```bash
 cd ../
 tox -e build
-cd tests/
 tox -e func-smoke
 ```