Chore: Update ghcr.io/renovatebot/renovate Docker tag to v39.31.4

Author: grafanarenovatebot[bot]

.github/workflows/renovate-validate.yaml

@@ -13,5 +13,5 @@ jobs:
       - name: Validate renovate config
         run: |-
           # Renovate updates the line below. Please keep its formatting as it is.
-          export RENOVATE_IMAGE=ghcr.io/renovatebot/renovate:39.31.0@sha256:ea2b64778453a944cc982b6bb42b7581a7d526cab1bb2fa09a13cacd5525c9fe
+          export RENOVATE_IMAGE=ghcr.io/renovatebot/renovate:39.31.4@sha256:2fe784c7ce2515a7a6a48fb18ae80cb99c81dffb143bb1a7d1f931c3f95baf53
           docker run -i --rm -v $(realpath .):/repo -w /repo --entrypoint renovate-config-validator "$RENOVATE_IMAGE" --strict

.github/workflows/renovate.yaml

@@ -37,7 +37,7 @@ jobs:
       - name: Self-hosted Renovate
         uses: renovatebot/github-action@dd4d265eb8646cd04fc5f86ff8bc8d496d75a251 # v40.2.8
         with:
-          renovate-version: 39.31.0@sha256:ea2b64778453a944cc982b6bb42b7581a7d526cab1bb2fa09a13cacd5525c9fe
+          renovate-version: 39.31.4@sha256:2fe784c7ce2515a7a6a48fb18ae80cb99c81dffb143bb1a7d1f931c3f95baf53
           configurationFile: .github/renovate-app.json
           token: "${{ steps.app-token.outputs.token }}"
         env: