Bump Python requirement lxml to 5.2.0

requirements.txt

@@ -4,7 +4,7 @@ boto3==1.26.124
 flashlight-text==0.0.4
 imageio==2.26.1
 imagesize==1.4.1
-lxml==4.9.3
+lxml==5.2.0
 matplotlib==3.8.3
 mdutils==1.6.0
 nltk==3.8.1