Try changing syntax to assign GITHUB_ENV

.github/workflows/release.yml

@@ -147,7 +147,7 @@ jobs:
       run: |
         micromamba activate eos_build
         $env:RELEASE_TAG = (python -c "import eos;print('v'+eos.__version__)")
-        echo "RELEASE_TAG=$env:RELEASE_TAG" >> $env:GITHUB_ENV
+        echo "RELEASE_TAG=$env:RELEASE_TAG" | Out-File -FilePath $env:GITHUB_ENV -Append
 
         echo "Set tag to $env:RELEASE_TAG"
         #pyinstaller windows_build.spec