Fixed CodeBlock deprecation warning on Sphinx 2.1+.
@@ -10,7 +10,7 @@ from docutils.parsers.rst import Directive
from docutils.statemachine import ViewList
from sphinx import addnodes
from sphinx.builders.html import StandaloneHTMLBuilder
-from sphinx.directives import CodeBlock
+from sphinx.directives.code import CodeBlock
from sphinx.errors import SphinxError
from sphinx.domains.std import Cmdoption
from sphinx.errors import ExtensionError
