build(deps): bump golang from 1.18.2-alpine3.15 to 1.18.3-alpine3.15

Bumps golang from 1.18.2-alpine3.15 to 1.18.3-alpine3.15.

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

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

Dockerfile

 ARG BASE_IMAGE=alpine
 
-FROM golang:1.18.2-alpine3.15 AS builder
+FROM golang:1.18.3-alpine3.15 AS builder
 
 WORKDIR /usr/local/src/dex