Dockerfile: Update to namespace for some labels

Using "MAINTAINER" and "Description" have been replaced with
org.opencontainers.image namespace variables.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/tools/docker/Dockerfile b/tools/docker/Dockerfile
index cda8735..f0e3699 100644
--- a/tools/docker/Dockerfile
+++ b/tools/docker/Dockerfile
@@ -3,8 +3,8 @@
 # to build U-Boot and run our test suites.
 
 FROM ubuntu:jammy-20240227
-MAINTAINER Tom Rini <trini@konsulko.com>
-LABEL Description=" This image is for building U-Boot inside a container"
+LABEL org.opencontainers.image.authors="Tom Rini <trini@konsulko.com>"
+LABEL org.opencontainers.image.description=" This image is for building U-Boot inside a container"
 
 # Make sure apt is happy
 ENV DEBIAN_FRONTEND=noninteractive