GH Actions: fix use of deprecated set-output (#136)

GitHub has deprecated the use of `set-output` (and `set-state`) in favour of new environment files.

This commit updates workflows to use the new methodology.

Refs:
* https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
* https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#environment-files

Co-authored-by: jrfnl <[email protected]>

.github/workflows/test.yml

@@ -114,14 +114,14 @@ jobs:
         run: |
           if [[ "${{ matrix.wp }}" =~ ^(trunk|latest|5\.9|[6789]\.[0-9])$ ]]; then
             if [[ "${{ matrix.php }}" != "8.2" ]]; then
-              echo '::set-output name=TYPE::1'
+              echo 'TYPE=1' >> $GITHUB_OUTPUT
             else
-              echo '::set-output name=TYPE::2'
+              echo 'TYPE=2' >> $GITHUB_OUTPUT
             fi
           elif [[ "${{ matrix.php }}" > "7.4" ]]; then
-            echo '::set-output name=TYPE::4'
+            echo 'TYPE=4' >> $GITHUB_OUTPUT
           else
-            echo '::set-output name=TYPE::3'
+            echo 'TYPE=3' >> $GITHUB_OUTPUT
           fi
 
       # Remove the PHPUnit requirement for WP 5.9 and higher in favour of letting the Polyfills manage it.