chore: bump golang from 1.21.5-alpine3.18 to 1.21.6-alpine3.18 (#43)

Bumps golang from 1.21.5-alpine3.18 to 1.21.6-alpine3.18.

---
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

@@ -1,6 +1,6 @@
 FROM --platform=$BUILDPLATFORM tonistiigi/xx:1.3.0@sha256:904fe94f236d36d65aeb5a2462f88f2c537b8360475f6342e7599194f291fb7e AS xx
 
-FROM --platform=$BUILDPLATFORM golang:1.21.5-alpine3.18@sha256:d8b99943fb0587b79658af03d4d4e8b57769b21dcf08a8401352a9f2a7228754 AS builder
+FROM --platform=$BUILDPLATFORM golang:1.21.6-alpine3.18@sha256:869193e7c30611d635c7bc3d1ed879039b7d24710a03474437d402f06825171e AS builder
 
 COPY --from=xx / /