Bump golang from 1.19-alpine to 1.21-alpine

Bumps golang from 1.19-alpine to 1.21-alpine.

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
...

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

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.19-alpine AS build
+FROM golang:1.21-alpine AS build
 COPY . /go/src/jacobbednarz/go-csp-collector
 WORKDIR /go/src/jacobbednarz/go-csp-collector
 RUN set -ex \