ci: Use GITHUB_OUTPUT envvar instead of set-output command (#543)

`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/chart-lint-and-test.yml

@@ -54,8 +54,8 @@ jobs:
           changed=$(ct --config ./.github/configs/ct-lint.yaml list-changed)
           charts=$(echo "$changed" | tr '\n' ' ' | xargs)
           if [[ -n "$changed" ]]; then
-            echo "::set-output name=changed::true"
-            echo "::set-output name=changed_charts::$charts"
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+            echo "changed_charts=$charts" >> "$GITHUB_OUTPUT"
           fi
 
       - name: Run Artifact Hub lint

.github/workflows/run-acceptance-tests.yaml

@@ -16,7 +16,7 @@ jobs:
     steps:
       - name: Create URL to the run output
         id: vars
-        run: echo ::set-output name=run-url::https://github.com/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID
+        run: echo run-url=https://github.com/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID >> "$GITHUB_OUTPUT"
       - name: Update with Result
         uses: peter-evans/create-or-update-comment@v1
         with:

.github/workflows/weekly-pulumi-update.yml

@@ -41,7 +41,7 @@ jobs:
           make dep-tidy
           git update-index -q --refresh
           if ! git diff-files --quiet; then
-            echo ::set-output name=changes::1
+            echo changes=1 >> "$GITHUB_OUTPUT"
           fi
       - name: Build codegen + Schema + SDKs
         if: steps.gomod.outputs.changes != 0