Bump alpine from 3.15.2 to 3.15.3 (#739)

Bumps alpine from 3.15.2 to 3.15.3.

---
updated-dependencies:
- dependency-name: alpine
  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

@@ -15,7 +15,7 @@ RUN go get -u github.com/gobuffalo/packr/v2/packr2
 COPY . .
 RUN packr2 build -a -o polaris *.go
 
-FROM alpine:3.15.2
+FROM alpine:3.15.3
 WORKDIR /usr/local/bin
 RUN apk --no-cache add ca-certificates