Bump django from 2.1.6 to 2.1.9 in /examples/cookbook-plain

Bumps [django](https://github.com/django/django) from 2.1.6 to 2.1.9. - [Release notes](https://github.com/django/django/releases) - [Commits](django/django@2.1.6...2.1.9) Signed-off-by: dependabot[bot] <support@github.com>
graphql-python · Jun 17, 2019 · 958a846 · 958a846
1 parent 6169346
commit 958a846
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/examples/cookbook-plain/requirements.txt b/examples/cookbook-plain/requirements.txt
@@ -1,4 +1,4 @@
 graphene
 graphene-django
 graphql-core>=2.1rc1
-django==2.1.6
+django==2.1.9