[librsvg: 1/21] CI: install Sphinx in the opensuse-stable container

[Marge Bot <marge-bot src gnome org>]

commit c9e5976608d7ca4c090c3bb2557efadae96e667f
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Jun 14 10:21:24 2022 -0500

    CI: install Sphinx in the opensuse-stable container
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/729>

 ci/container_builds.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/ci/container_builds.yml b/ci/container_builds.yml
index e532ac323..2640515e5 100644
--- a/ci/container_builds.yml
+++ b/ci/container_builds.yml
@@ -6,7 +6,7 @@ include:
 variables:
   # When branching change the suffix to avoid conflicts with images
   # from the main branch
-  BASE_TAG: "2022-08-05.0-main"
+  BASE_TAG: "2022-08-15.0-devel-docs"
   RUST_STABLE: "1.60.0"
   RUST_MINIMUM: "1.58.1"
 
@@ -32,7 +32,8 @@ variables:
     FDO_DISTRIBUTION_TAG: "x86_64-${RUST_STABLE}-${BASE_TAG}"
     FDO_DISTRIBUTION_EXEC: >-
       bash ci/install-rust.sh ${RUST_STABLE} x86_64-unknown-linux-gnu &&
-      pip3 install gi-docgen
+      pip3 install gi-docgen &&
+      pip3 install sphinx
 
 .container.opensuse@x86_64.minimum:
   extends: .container.opensuse@common