Replace set-output command

Author: doctorperceptron

.github/workflows/post_release_version_bump.yml

@@ -18,8 +18,8 @@ jobs:
           old_version=`grep -oP '(?<=__version__ = ").*(?=")' xanadu_sphinx_theme/_version.py`
           new_version=`echo $old_version | awk '{split($0,v,"."); print v[1] "." v[2]+1 ".0-dev"}'`
 
-          echo "::set-output name=old_version::$old_version"
-          echo "::set-output name=new_version::$new_version"
+          echo "old_version=$old_version" >> $GITHUB_OUTPUT
+          echo "new_version=$new_version" >> $GITHUB_OUTPUT
 
       - name: Bump version in _version.py
         run:
@@ -49,4 +49,4 @@ jobs:
             to `${{ steps.versions.outputs.new_version }}`.
           commit-message: Bump version to `${{ steps.versions.outputs.new_version }}`
           branch: post-release-version-bump
-          reviewers: mandrenkov, josh146
+          reviewers: mandrenkov, josh146