Actually set the output for the pyenv version

Author: jb3

.github/workflows/build-root.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Get latest pyenv version
         id: get_pyenv_version
         run: |
-          git describe --abbrev=0 --tags
+          echo "pyenv_version=$(git describe --abbrev=0 --tags)" >> $GITHUB_OUTPUT
 
   build-base:
     name: Build Python Builder Base