diff --git a/examples/CH_11/requirements.txt b/examples/CH_11/requirements.txt
old mode 100755
new mode 100644
index 81569f4..4a80939
--- a/examples/CH_11/requirements.txt
+++ b/examples/CH_11/requirements.txt
@@ -3,7 +3,7 @@ bcrypt==3.2.0
 bleach==5.0.1
 blinker==1.4
 cachetools==5.0.0
-certifi==2022.12.7
+certifi==2023.7.22
 cffi==1.15.0
 charset-normalizer==2.0.12
 click==8.0.4