Reduce celery version

Author: johannalberts

requirements/edx/base.txt

@@ -26,13 +26,13 @@ appdirs==1.4.4            # via fs
 attrs==19.3.0             # via -r requirements/edx/base.in, edx-ace
 babel==2.8.0              # via -r requirements/edx/base.in, enmerkar, enmerkar-underscore
 beautifulsoup4==4.9.1     # via pynliner
-billiard==3.6.3.0        # via celery
+billiard==3.3.0.23        # via celery
 bleach==3.1.5             # via -r requirements/edx/base.in, edx-enterprise, lti-consumer-xblock, ora2
 boto3==1.4.8              # via -r requirements/edx/base.in, fs-s3fs
 boto==2.39.0              # via -r requirements/edx/base.in, django-ses, edxval, ora2
 botocore==1.8.17          # via -r requirements/edx/base.in, boto3, s3transfer
 bridgekeeper==0.9         # via -r requirements/edx/base.in
-celery==4.4.7      # via -c requirements/edx/../constraints.txt, -r requirements/edx/base.in, django-celery, django-user-tasks, edx-celeryutils, edx-enterprise
+celery==3.1.26            # via -c requirements/edx/../constraints.txt, -r requirements/edx/base.in, django-celery, django-user-tasks, edx-celeryutils, edx-enterprise
 certifi==2020.6.20        # via -r requirements/edx/paver.txt, requests
 cffi==1.14.0              # via -r requirements/edx/../edx-sandbox/shared.txt, cryptography
 chardet==3.0.4            # via -r requirements/edx/paver.txt, pdfminer.six, pysrt, requests
@@ -140,7 +140,7 @@ jmespath==0.10.0          # via boto3, botocore
 joblib==0.14.1            # via -c requirements/edx/../constraints.txt, -r requirements/edx/../edx-sandbox/shared.txt, nltk
 jsondiff==1.2.0           # via edx-enterprise
 jsonfield2==3.0.3         # via -c requirements/edx/../constraints.txt, -r requirements/edx/base.in, edx-celeryutils, edx-enterprise, edx-proctoring, edx-submissions, ora2
-kombu==4.6.10             # via celery
+kombu==3.0.37             # via celery
 laboratory==1.0.2         # via -r requirements/edx/base.in
 lazy==1.4                 # via -r requirements/edx/paver.txt, acid-xblock, lti-consumer-xblock, ora2
 lepl==5.1.3               # via rfc6266-parser