also enable CoW when enabling future.infer_string

Author: jorisvandenbossche

.github/workflows/unit-tests.yml

@@ -106,6 +106,7 @@ jobs:
             env_file: actions-311-pyarrownightly.yaml
             pattern: "not slow and not network and not single_cpu"
             pandas_future_infer_string: "1"
+            pandas_copy_on_write: "1"
       fail-fast: false
     name: ${{ matrix.name || format('ubuntu-latest {0}', matrix.env_file) }}
     env: