build(deps): update golang docker tag to v1.21.5

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Dockerfile

@@ -1,7 +1,7 @@
 # Use the offical Golang image to create a build artifact.
 # This is based on Debian and sets the GOPATH to /go.
 # https://hub.docker.com/_/golang
-FROM golang:1.17.5-alpine as builder
+FROM golang:1.21.5-alpine as builder
 RUN apk add --no-cache gcc libc-dev git
 
 ARG version=develop