chore(deps): Bump golang from 1.25-alpine to 1.26-alpine in /docker

Bumps golang from 1.25-alpine to 1.26-alpine.

---
updated-dependencies:
- dependency-name: golang
  dependency-version: 1.26-alpine
  dependency-type: direct:production
...

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

Author: dependabot[bot]

docker/go.Dockerfile

@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1.4
 # Go execution environment with BuildKit optimizations
-FROM golang:1.25-alpine
+FROM golang:1.26-alpine
 
 # Install common tools
 RUN apk add --no-cache \