Update ci/local/build.sh default $DOCKER_IMAGE (#8013)

`DOCKER_IMAGE` is out of date since #7953 was merged. This fixes that.

Authors:
  - Conor Hoekstra (https://github.com/codereport)

Approvers:
  - AJ Schmidt (https://github.com/ajschmidt8)

URL: #8013

ci/local/build.sh

@@ -3,7 +3,7 @@
 GIT_DESCRIBE_TAG=`git describe --tags`
 MINOR_VERSION=`echo $GIT_DESCRIBE_TAG | grep -o -E '([0-9]+\.[0-9]+)'`
 
-DOCKER_IMAGE="gpuci/rapidsai:${MINOR_VERSION}-cuda10.1-devel-ubuntu16.04-py3.7"
+DOCKER_IMAGE="gpuci/rapidsai:${MINOR_VERSION}-cuda11.0-devel-ubuntu18.04-py3.7"
 REPO_PATH=${PWD}
 RAPIDS_DIR_IN_CONTAINER="/rapids"
 CPP_BUILD_DIR="cpp/build"