ci: Use GITHUB_OUTPUT envvar instead of set-output command

`save-state` and `set-output` commands used in GitHub Actions are deprecated and [GitHub recommends using environment files](https://github.blog/changelog/2023-07-24-github-actions-update-on-save-state-and-set-output-commands/).

This PR updates the usage of `::set-output` to `"$GITHUB_OUTPUT"`

Instructions for envvar usage from GitHub docs:

https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-output-parameter

.github/workflows/publish-extension.yml

@@ -41,7 +41,7 @@ jobs:
 
       - name: Setup package path
         id: setup
-        run: echo "::set-output name=packageName::$(node -e "console.log(require('./package.json').name + '-' + require('./package.json').version + '.vsix')")"
+        run: echo "packageName=$(node -e "console.log(require('./package.json').name + '-' + require('./package.json').version + '.vsix')")" >> "$GITHUB_OUTPUT"
 
       - name: Package
         run: |
@@ -58,8 +58,8 @@ jobs:
         run: |
           $version = (Get-Content ./package.json -Raw | ConvertFrom-Json).version
           Write-Host "tag: v$version"
-          Write-Host "::set-output name=tag::v$version"
-          Write-Host "::set-output name=version::$version"
+          Write-Host "tag=v$version" >> "$GITHUB_OUTPUT"
+          Write-Host "version=$version" >> "$GITHUB_OUTPUT"
         shell: pwsh
 
   publishMS: