chore(deps): bump alpine from 3.15.3 to 3.15.4

Bumps alpine from 3.15.3 to 3.15.4.

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

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

Dockerfile

@@ -3,7 +3,7 @@ FROM golang:1.18.0-alpine AS build-env
 RUN go install -v github.com/projectdiscovery/subfinder/v2/cmd/subfinder@latest
 
 # Release
-FROM alpine:3.15.3
+FROM alpine:3.15.4
 RUN apk -U upgrade --no-cache \
     && apk add --no-cache bind-tools ca-certificates
 COPY --from=build-env /go/bin/subfinder /usr/local/bin/subfinder