chore(deps): update golang docker tag to v1.26.6 (#649)

This PR contains the following updates:

| Package | Type | Update | Change | Pending |
|---|---|---|---|---|
| [golang](https://hub.docker.com/_/golang)
([source](https://redirect.github.com/docker-library/golang)) | stage |
patch | `1.26.5-alpine` → `1.26.6-alpine` | `1.27.0-alpine` (+1) |

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Dockerfile

@@ -27,7 +27,7 @@ RUN set -eux; \
 # Used by compose.yml's ldap-manager-dev / ldap-manager-test services.
 # Not part of the release pipeline — `docker buildx build --target=dev`
 # only locally. Source code is bind-mounted at runtime.
-FROM golang:1.26.5-alpine AS dev
+FROM golang:1.26.6-alpine AS dev
 
 SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
 WORKDIR /app