Remove Requests dependencies

requirements.txt

@@ -4,10 +4,8 @@ apistar==0.7.2
 git+https://gitlab.com/teklia/apistar.git#egg=apistar
 arkindex-common==0.2.0
 git+https://gitlab.com/arkindex/common.git#egg=arkindex-common
-certifi==2020.6.20
 channels==2.4.0
 channels-redis==3.1.0
-chardet==3.0.4
 django-admin-hstore-widget==1.1.0
 django-cachalot==2.3.1
 django-cors-headers==3.5.0
@@ -16,7 +14,6 @@ django-redis==4.12.1
 djangorestframework==3.11.1
 elasticsearch-dsl>=6.0.0,<7.0.0
 gitpython==3.0.8
-idna==2.10
 python-gitlab==1.7.0
 python-memcached==1.59
 pytz==2020.1
@@ -28,4 +25,3 @@ tenacity==6.2
 transkribus-client>=0.1.1
 git+https://gitlab.com/arkindex/transkribus.git#egg=transkribus-client
 uritemplate==3
-urllib3==1.22