lets see if the variable sets correctly now

.github/workflows/release.yml

@@ -16,7 +16,7 @@ jobs:
     steps:
       - name: download mpv
         run: |
-          api = $(curl "https://api.github.com/repos/shinchiro/mpv-winbuild-cmake/releases/latest" | python -c "import sys, json; print(json.load(sys.stdin)['assets'][9]['browser_download_url'])")
+          echo api=$(curl "https://api.github.com/repos/shinchiro/mpv-winbuild-cmake/releases/latest" | python -c "import sys, json; print(json.load(sys.stdin)['assets'][9]['browser_download_url'])")" >> $GITHUB_ENV
           curl $api -o mpv.7z
           7z x mpv.7z -ompv/