Add OCI source annotation to link back to source repo (#701)

* Add OCI source annotation to link back to source repo

This commit adds the `org.opencontainers.image.source` label to the
built container images.

This label is helpful for tools to be able to link back from the
container image to the source repo.

For example, for those that use Renovate to help auto update
dependencies, this will result in the latest releases release
notes/changelog being included in the PR which is very handy!

* move label to base image

---------

Co-authored-by: Sascha Ißbrücker <sascha.issbruecker@googlemail.com>

docker/alpine.Dockerfile

@@ -69,6 +69,7 @@ RUN wget https://www.sqlite.org/${SQLITE_RELEASE_YEAR}/sqlite-amalgamation-${SQL
 
 
 FROM python:3.11.8-alpine3.19 AS linkding
+LABEL org.opencontainers.image.source="https://github.com/sissbruecker/linkding"
 # install runtime dependencies
 RUN apk update && apk add bash curl icu libpq mailcap libssl3
 # create www-data user and group

docker/default.Dockerfile

@@ -71,6 +71,7 @@ RUN wget https://www.sqlite.org/${SQLITE_RELEASE_YEAR}/sqlite-amalgamation-${SQL
 
 
 FROM python:3.11.8-slim-bookworm as linkding
+LABEL org.opencontainers.image.source="https://github.com/sissbruecker/linkding"
 RUN apt-get update && apt-get -y install mime-support libpq-dev libicu-dev libssl3 curl
 WORKDIR /etc/linkding
 # copy prod dependencies