[ci] run miri on ArrayVec

Author: andresilva

.github/workflows/slow.yml

@@ -194,6 +194,10 @@ jobs:
       run: |
         cd runtime
         just miri iobuf:: --partition hash:${{matrix.partition}}/8
+    - name: Run miri tests for utils::vec::array
+      run: |
+        cd utils
+        just miri vec::array::tests --partition hash:${{matrix.partition}}/8
 
   Unsafe-Tests-Gate:
     name: "Unsafe-Tests"