Add flext->flex (#1538)

Co-authored-by: tikuta <tikuta@chromium.org>

codespell_lib/data/dictionary.txt

diff --git a/codespell_lib/data/dictionary.txt b/codespell_lib/data/dictionary.txt
index e2800fa..68355b9 100644
--- a/codespell_lib/data/dictionary.txt
+++ b/codespell_lib/data/dictionary.txt
@@ -11967,6 +11967,7 @@
 flexable->flexible
 flexibel->flexibele
 flexibilty->flexibility
+flext->flex
 flie->file
 floading->floating, flooding,
 floading-add->floating-add