fix windows python environment invocation (path separators)

Author: jcschaff

.github/workflows/on-release-main.yml

@@ -57,7 +57,7 @@ jobs:
 
       - name: Build and publish (Windows)
         run: |
-          .venv\Scripts\activate
+          .venv/Scripts/activate
           poetry version $RELEASE_VERSION
           make build-and-publish
         env: