[PATCH v2 1/2] gitlab/opensbi: Move to docker:stable

[Palmer Dabbelt]

The OpenSBI build has been using docker:19.03.1, which appears to be old
enough that v2 of the manifest is no longer supported.  Something has
started serving us those manifests, resulting in errors along the lines
of

    $ docker build --cache-from $IMAGE_TAG --tag 
$CI_REGISTRY_IMAGE:$CI_COMMIT_SHA --tag $IMAGE_TAG .gitlab-ci.d/opensbi
    Step 1/7 : FROM ubuntu:18.04
    18.04: Pulling from library/ubuntu
    mediaType in manifest should be 
'application/vnd.docker.distribution.manifest.v2+json' not 
'application/vnd.oci.image.manifest.v1+json'

This moves to docker:stable, as was suggested by the template.  It also
adds the python3 package via apt, as OpenSBI requires that to build.

Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
---
 .gitlab-ci.d/opensbi.yml        | 4 ++--
 .gitlab-ci.d/opensbi/Dockerfile | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/.gitlab-ci.d/opensbi.yml b/.gitlab-ci.d/opensbi.yml
index 04ed5a3ea1..9a651465d8 100644
--- a/.gitlab-ci.d/opensbi.yml
+++ b/.gitlab-ci.d/opensbi.yml
@@ -42,9 +42,9 @@
 docker-opensbi:
   extends: .opensbi_job_rules
   stage: containers
-  image: docker:19.03.1
+  image: docker:stable
   services:
-    - docker:19.03.1-dind
+    - docker:stable-dind
   variables:
     GIT_DEPTH: 3
     IMAGE_TAG: $CI_REGISTRY_IMAGE:opensbi-cross-build
diff --git a/.gitlab-ci.d/opensbi/Dockerfile b/.gitlab-ci.d/opensbi/Dockerfile
index 4ba8a4de86..2d151a6bc8 100644
--- a/.gitlab-ci.d/opensbi/Dockerfile
+++ b/.gitlab-ci.d/opensbi/Dockerfile
@@ -16,6 +16,7 @@ RUN apt update \
         git \
         make \
         wget \
+       python3 \
     && \
     \
     rm -rf /var/lib/apt/lists/*
-- 
2.39.2