[indico-web] worker: Install certifi

[Bartłomiej Piotrowski <bpiotrowski src gnome org>]

commit ab580a8cd1e79d89662991ecda61799800aa43c4
Author: Bartłomiej Piotrowski <bpiotrowski gnome org>
Date:   Tue Dec 3 12:54:59 2019 +0100

    worker: Install certifi

 worker/Dockerfile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/worker/Dockerfile b/worker/Dockerfile
index 2f60e80..45f7e38 100644
--- a/worker/Dockerfile
+++ b/worker/Dockerfile
@@ -11,7 +11,7 @@ RUN apt-get update && \
 RUN virtualenv ${INDICO_VIRTUALENV}
 RUN ${pip} install --upgrade pip setuptools && \
     ${pip} install uwsgi raven && \
-    ${pip} install indico indico-plugins python-ldap
+    ${pip} install indico indico-plugins python-ldap certifi
 RUN chgrp -R 0 /opt/indico
 
 FROM python:2.7-buster