Bump alpine from 3.14 to 3.15.0

Bumps alpine from 3.14 to 3.15.0.

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

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

Author: dependabot[bot]

Dockerfile

@@ -29,7 +29,7 @@ RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build \
         -X github.com/openfaas/faas-netes/version.Version=${VERSION}" \
         -a -installsuffix cgo -o faas-netes .
 
-FROM --platform=${TARGETPLATFORM:-linux/amd64} alpine:3.14 as ship
+FROM --platform=${TARGETPLATFORM:-linux/amd64} alpine:3.15.0 as ship
 LABEL org.label-schema.license="MIT" \
       org.label-schema.vcs-url="https://github.com/openfaas/faas-netes" \
       org.label-schema.vcs-type="Git" \