Update lxml, pypdf2 requirement

requirements.txt

@@ -7,14 +7,14 @@ Flask-Principal>=0.3.2,<0.5.1
 backports_abc>=0.4
 Flask>=1.0.2,<2.1.0
 iso-639>=0.4.5,<0.5.0
-PyPDF2>=1.20,<2.11.0
+PyPDF2>=1.20,<3.1.0
 pytz>=2016.10
 requests>=2.11.1,<2.28.0
 SQLAlchemy>=1.3.0,<1.5.0
 tornado>=4.1,<6.2
 Wand>=0.4.4,<0.7.0
 unidecode>=0.04.19,<1.4.0
-lxml>=3.8.0,<4.9.0
+lxml>=3.8.0,<5.0.0
 flask-wtf>=0.14.2,<1.1.0
 chardet>=3.0.0,<4.1.0
 advocate>=1.0.0,<1.1.0