docker: bump golang from 5c1cabd to 9390a99 (#433)

Bumps golang from `5c1cabd` to `9390a99`.

---
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-alpine3.18@sha256:5c1cabd9a3c6851a3e18735a2c133fbd8f67fe37eb3203318b7af2ffd2547095 AS build
+FROM golang:1.21.5-alpine3.18@sha256:9390a996e9f957842f07dff1e9661776702575dd888084e72d86eaa382ad56e3 AS build
 
 COPY . /go/src/github.com/jauderho/bl3auto
 WORKDIR /go/src/github.com/jauderho/bl3auto