Update quay.io/helmpack/chart-testing Docker tag to v3.12.0 (#3016)

| datasource | package                        | from    | to      |
| ---------- | ------------------------------ | ------- | ------- |
| docker     | quay.io/helmpack/chart-testing | v3.11.0 | v3.12.0 |

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Makefile

@@ -35,7 +35,7 @@ CONTROLLER_TOOLS_VERSION = v0.17.1
 # renovate: datasource=docker depName=node
 NODE_VERSION = 22
 # renovate: datasource=docker depName=quay.io/helmpack/chart-testing
-CHART_TESTING_VERSION = v3.11.0
+CHART_TESTING_VERSION = v3.12.0
 # renovate: datasource=github-tags depName=dadav/helm-schema
 HELM_SCHEMA_VERSION = 0.18.1