chore(deps): update docker/metadata-action action to v6

| datasource  | package                | from    | to     |
| ----------- | ---------------------- | ------- | ------ |
| github-tags | docker/metadata-action | v5.10.0 | v6.0.0 |


Signed-off-by: renovate-sh-app[bot] <219655108+renovate-sh-app[bot]@users.noreply.github.com>

Author: renovate-sh-app[bot]

.github/workflows/build-doc-generator.yaml

@@ -29,7 +29,7 @@ jobs:
 
       - name: Docker meta
         id: meta
-        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051  # v5.10.0
+        uses: docker/metadata-action@030e881283bb7a6894de51c315a6bfe6a94e05cf  # v6.0.0
         with:
           images: ghcr.io/grafana/helm-chart-toolbox-doc-generator
           tags: |

.github/workflows/build-schema-generator.yaml

@@ -29,7 +29,7 @@ jobs:
 
       - name: Docker meta
         id: meta
-        uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051  # v5.10.0
+        uses: docker/metadata-action@030e881283bb7a6894de51c315a6bfe6a94e05cf  # v6.0.0
         with:
           images: ghcr.io/grafana/helm-chart-toolbox-schema-generator
           tags: |