[fix] drop 'idna' from requirements.txt
@@ -2,7 +2,6 @@ certifi==2020.12.05
babel==2.9.0
flask-babel==2.0.0
flask==1.1.2
-idna==2.10
jinja2==2.11.3
lxml==4.6.3
pygments==2.8.1