workflows: stop hardcoding openslide-bin zip URL template

Use `gh release download` instead.

Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>

.github/workflows/python.yml

@@ -179,7 +179,8 @@ jobs:
             jq -r .[0].tagName | \
             tr -d v)
         zipname="openslide-win64-${release}"
-        curl -LfO "https://github.com/openslide/openslide-bin/releases/download/v${release}/${zipname}.zip"
+        gh release download -R openslide/openslide-bin "v${release}" \
+            --pattern "${zipname}.zip"
         7z x ${zipname}.zip
         echo "OPENSLIDE_PATH=c:\\openslide\\${zipname}\\bin" >> $GITHUB_ENV
     - name: Build wheel