build(deps): bump golang in /shared/golang

Bumps golang from 1.25.6-bookworm to 1.26.1-bookworm.

---
updated-dependencies:
- dependency-name: golang
  dependency-version: 1.26.1-bookworm
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

shared/golang/Dockerfile

@@ -3,7 +3,7 @@ RUN rm -f /etc/apt/apt.conf.d/docker-clean \
     && echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' | tee /etc/apt/apt.conf.d/keep-cache
 
 
-FROM golang:1.25.6-bookworm@sha256:2f768d462dbffbb0f0b3a5171009f162945b086f326e0b2a8fd5d29c3219ff14 AS golang-base
+FROM golang:1.26.1-bookworm@sha256:c7a82e9e2df2fea5d8cb62a16aa6f796d2b2ed81ccad4ddd2bc9f0d22936c3f2 AS golang-base
 
 
 FROM golang-base AS golang-control-plane-builder