ci: add release workflow; add OCI version/revision labels

Dockerfile

@@ -20,8 +20,13 @@ RUN CGO_ENABLED=0 GOOS=linux go build -o server main.go
 FROM alpine:latest
 WORKDIR /root/
 
+ARG IMAGE_VERSION=dev
+ARG IMAGE_REVISION=
+
 LABEL org.dcntrlized.service=KeepNote
 LABEL org.dcntrlized.port=8080
+LABEL org.opencontainers.image.version=$IMAGE_VERSION
+LABEL org.opencontainers.image.revision=$IMAGE_REVISION
 
 COPY --from=builder /app/server .