Upgrade to Celery 5.1.2

There are several other changes we need to make in order to install
the new version. For more context, see:

- 208e90e40f
- e3d1993a58
- 7e93611fce

In the next commits we'll look at tidying up the config and other
dependencies so the change is deployable.

requirements-app.txt

@@ -2,7 +2,7 @@
 # with package version changes made in requirements-app.txt
 
 cffi==1.14.5
-celery[sqs]==3.1.26.post2 # pyup: <4
+celery[sqs]==5.1.2
 docopt==0.6.2
 Flask-Bcrypt==0.7.1
 flask-marshmallow==0.14.0

requirements.txt

@@ -4,7 +4,7 @@
 # with package version changes made in requirements-app.txt
 
 cffi==1.14.5
-celery[sqs]==3.1.26.post2 # pyup: <4
+celery[sqs]==5.1.2
 docopt==0.6.2
 Flask-Bcrypt==0.7.1
 flask-marshmallow==0.14.0
@@ -46,12 +46,12 @@ gds-metrics==0.2.4
 
 ## The following requirements were added by pip freeze:
 alembic==1.7.4
-amqp==1.4.9
+amqp==5.0.6
 anyjson==0.3.3
 attrs==21.2.0
 awscli==1.21.4
 bcrypt==3.2.0
-billiard==3.3.0.23
+billiard==3.6.4.0
 bleach==4.1.0
 blinker==1.4
 boto==2.49.0
@@ -59,7 +59,7 @@ boto3==1.19.4
 botocore==1.22.4
 certifi==2021.10.8
 charset-normalizer==2.0.7
-click==8.0.3
+click==7.1.2
 colorama==0.4.3
 dataclasses==0.8
 dnspython==1.16.0
@@ -73,7 +73,7 @@ importlib-metadata==4.8.1
 importlib-resources==5.3.0
 Jinja2==3.0.2
 jmespath==0.10.0
-kombu==3.0.37
+kombu==5.1.0
 Mako==1.1.5
 MarkupSafe==2.0.1
 mistune==0.8.4