Merge ~cjwatson/launchpad:contextvars-2.4 into launchpad:master

[Colin Watson]

Add contextvars 2.4 and immutables 0.14

These are dependencies of talisker on Python 3.5 and 3.6.

Dependencies MP: https://code.launchpad.net/~cjwatson/lp-source-dependencies/+git/lp-source-dependencies/+merge/396760

[Cristian Gonzalez (cristiangsp)]

review: Approve

diff --git a/requirements/launchpad.txt b/requirements/launchpad.txt
index 215976c..0605a51 100644
--- a/requirements/launchpad.txt
+++ b/requirements/launchpad.txt
@@ -24,6 +24,7 @@ botocore==1.19.2
 celery==4.1.1
 Chameleon==3.6.2
 configobj==5.0.6
+contextvars==2.4
 constantly==15.1.0
 contextlib2==0.6.0.post1
 cookies==2.2.1
@@ -49,6 +50,7 @@ grokcore.component==3.1
 gunicorn==19.8.1
 httplib2==0.8
 hyperlink==18.0.0
+immutables==0.14
 importlib==1.0.2
 importlib-resources==0.5
 incremental==17.5.0