chore: Update picklefield to remove warnings (#13251)

Allow using a newer version of picklefield that doesn't emit startup
warnings. I'll bump getsentry once this has landed.

Refs SEN-618

requirements-base.txt

@@ -9,7 +9,7 @@ croniter>=0.3.26,<0.4.0
 cssutils>=0.9.9,<0.10.0
 django-crispy-forms>=1.4.0,<1.5.0
 django-jsonfield>=0.9.13,<0.9.14
-django-picklefield>=0.3.0,<0.4.0
+django-picklefield>=0.3.0,<1.1.0
 django-sudo>=2.1.0,<3.0.0
 django-templatetag-sugar>=0.1.0
 Django>=1.8,<1.9