[Docs] Fix exception name being caught in case ReadTheDocs does not exist.

The exception is `ImportError`, not `ModuleNotFoundError`.

llvm-svn: 303982

diff --git a/polly/docs/conf.py b/polly/docs/conf.py
index 4fb1695..64d3968 100644 (file)
--- a/polly/docs/conf.py
+++ b/polly/docs/conf.py
@@ -96,7 +96,7 @@ try:
     import sphinx_rtd_theme
     html_theme = "sphinx_rtd_theme"
     html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-except ModuleNotFoundError:
+except ImportError:
     html_theme = 'haiku'