Add miniconda install=true to build_wheels_macos.yml (#6847)

Miniconda is required for M1 wheel builds

This action will, by default, activate an environment called test and
not activate the base environment. This encourages the recommended
practice of not installing workflow packages into the base environment
and leaving it with only conda (and/or mamba).

Author: atalman

.github/workflows/build_wheels_macos.yml

@@ -78,7 +78,7 @@ on:
         description: Set to true if setup-miniconda is needed
         required: false
         type: boolean
-        default: false
+        default: true
       delocate-wheel:
         description: "Whether to run delocate-wheel after building."
         required: false