zlib needed as test-dep

Author: h-vetinari

recipe/meta.yaml

@@ -99,6 +99,9 @@ outputs:
       run:
         - {{ pin_subpackage("libgoogle-cloud", exact=True) }}
         - nlohmann_json
+        # cannot load package wihout zlib because it's specified
+        # as required; if possible, this should be removed upstream
+        - zlib
     test:
       commands:
         - ./run_test_google_cloud_cpp.sh  # [not win]