chore(deps): update ghcr.io/renovatebot/renovate docker tag to v39.28.0 (#542)

Co-authored-by: grafanarenovatebot[bot] <146220760+grafanarenovatebot[bot]@users.noreply.github.com>

Author: grafanarenovatebot[bot]

.github/workflows/renovate.yml

@@ -65,7 +65,7 @@ jobs:
         with:
           configurationFile: .github/renovate-config.json5
           # renovate: datasource=docker depName=ghcr.io/renovatebot/renovate
-          renovate-version: 39.19.1@sha256:70c69d2523448834ae53111d6440d4ad199fe390845f0712ac4128e5740fe2d7
+          renovate-version: 39.28.0@sha256:7cf419a3177d4cff065f1fa589c80b603c80fa7c3e1792ef1bcad8267be67325
           token: ${{ steps.generate-token.outputs.token }}
         env:
           LOG_LEVEL: ${{ github.event_name == 'pull_request' && 'debug' || 'info' }}