Remove revision from Alpine Linux

This causes noise from dependabot, where it tries to bunch each
patch revision in a separate PR.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <[email protected]>

Author: alexellis

Dockerfile

@@ -28,7 +28,7 @@ RUN VERSION=$(git describe --all --exact-match `git rev-parse HEAD` | grep tags
         -X github.com/openfaas/faas-netes/version.Version=${VERSION}" \
         -a -installsuffix cgo -o faas-netes .
 
-FROM --platform=${TARGETPLATFORM:-linux/amd64} alpine:3.13.2 as ship
+FROM --platform=${TARGETPLATFORM:-linux/amd64} alpine:3.13 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" \