MAINT: Use newer features with old SDK

Author: HaoZeke

recipes/pyflowy/recipe.yaml

@@ -21,7 +21,7 @@ build:
     - win
   number: ${{ build_num }}
   string: h${{ hash }}_${{ build_num }}
-  script: ${{ PYTHON }} -m pip install . -vv --no-deps --no-build-isolation
+  script: CXXFLAGS="${CXXFLAGS} -D_LIBCPP_DISABLE_AVAILABILITY" ${{ PYTHON }} -m pip install . -vv --no-deps --no-build-isolation
 
 requirements:
   build: