build(deps): bump golang from 1.21.5-alpine to 1.21.6-alpine (#452)

Bumps golang from 1.21.5-alpine to 1.21.6-alpine.

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.21.5-alpine AS build
+FROM golang:1.21.6-alpine AS build
 
 WORKDIR /go/src/github.com/segmentio/chamber
 COPY . .