Updated deprecated set-output command

https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

.github/workflows/nuget.yml

@@ -18,7 +18,7 @@ jobs:
 
     - name: Extract branch name
       shell: bash
-      run: echo "##[set-output name=branch;]$(echo ${GITHUB_REF#refs/tags/v})"
+      run: echo "branch=$(echo ${GITHUB_REF#refs/tags/v})" >> $GITHUB_OUTPUT
       id: extract_branch
 
     - name: Setup NuGet