FixWheelReleaseWithBuildx: Build release without buildkit

The whole point of the release build is to sequentially do the release
then verify that it can be installed. With buildkit, these stages don't
happen in a linear order.

Signed-off-by: Gabe Goodhart <ghart@us.ibm.com>

Author: gabe-l-hart

ci/release.sh

@@ -6,6 +6,11 @@ cd $(dirname ${BASH_SOURCE[0]})/..
 # Get the tag for this release
 tag=$(echo $REF | cut -d'/' -f3-)
 
+# We explicitly don't want to run with buildkit so that the docker builds happen
+# in a linear fashion since our `release_test` stages intentionally don't
+# inherit from the stages where the publication happens.
+export DOCKER_BUILDKIT=0
+
 # Build the docker phase that will release and then test it
 docker build . \
     --target=release_test \