.github: ::set-output is deprecated

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

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/weekly.yml

@@ -17,7 +17,12 @@ jobs:
       - name: Check for any commits since last week
         id: check
         run: |
-          echo '::set-output name=run::'$(test -n "$(git log --format=%H --since='1 week ago')" && echo 'true' || echo 'false')
+          commits="$(git log --format=%H --since='1 week ago')"
+          if [ -n "$commits" ]; then
+              echo run=true  >> $GITHUB_OUTPUT
+          else
+              echo run=false >> $GITHUB_OUTPUT
+          fi
 
   distcheck:
     needs: schedule