tinkerbell: Move to fedora based image
`cfssl` package for alpine has been removed. Hence the build fails. This
commit moves to a fedora based image.
-FROM alpine:3.11
+FROM registry.fedoraproject.org/fedora:34
ENTRYPOINT [ "/entrypoint.sh" ]
-RUN apk add --no-cache --update --upgrade ca-certificates postgresql-client
-RUN apk add --no-cache --update --upgrade --repository=http://dl-cdn.alpinelinux.org/alpine/edge/testing cfssl
+RUN dnf install --setopt=tsflags=nodocs -y \
+ postgresql \
+ golang-github-cloudflare-cfssl
COPY . .
