Revert "Disable deploy slides"

This reverts commit e2fafe4.

Author: astonzhang

Jenkinsfile

@@ -77,7 +77,7 @@ stage("Build and Publish") {
         sh label:"Release", script:"""set -ex
         conda activate ${ENV_NAME}
         d2lbook build pkg
-        d2lbook deploy html pdf pkg colab sagemaker --s3 s3://${LANG}-v2.d2l.ai
+        d2lbook deploy html pdf slides pkg colab sagemaker --s3 s3://${LANG}-v2.d2l.ai
         """
 
       } else {