Updated **lxml** version from `4.6.5` to `4.9.1`

requirements.txt

@@ -16,7 +16,7 @@ hpack==4.0.0; python_version >= "3.6" and python_full_version >= "3.6.1"
 httpcore==0.13.7; python_version >= "3.6"
 hyperframe==6.0.1; python_version >= "3.6" and python_full_version >= "3.6.1"
 idna==3.3; python_version >= "3.6" and (python_version >= "3.5" and python_full_version < "3.0.0" or python_full_version >= "3.6.0" and python_version >= "3.5") and python_full_version >= "3.6.2"
-lxml==4.6.5; python_version >= "2.7" and python_full_version < "3.10.0" or python_full_version >= "3.5.0"
+lxml==4.9.1; python_version >= "2.7" and python_full_version < "3.10.0" or python_full_version >= "3.5.0"
 prettyconf==2.2.1
 pyaes==1.6.1; python_version >= "3.6" and python_version < "4.0"
 pykeyboard==0.1.5