Chore: Update ghcr.io/renovatebot/renovate Docker tag to v39.26.1

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:39.14.1@sha256:65e8c6c295d33569995412053890b983cd01a6c8de643adb4d175889a27a07ed
+          export RENOVATE_IMAGE=ghcr.io/renovatebot/renovate:39.26.1@sha256:055b393c6ea92303ebf8f0cdbe04c9416826ac883c7f505e0cd1819398614b9e
           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: 39.14.1@sha256:65e8c6c295d33569995412053890b983cd01a6c8de643adb4d175889a27a07ed
+          renovate-version: 39.26.1@sha256:055b393c6ea92303ebf8f0cdbe04c9416826ac883c7f505e0cd1819398614b9e
           configurationFile: .github/renovate-app.json
           token: "${{ steps.app-token.outputs.token }}"
         env: