Merge pull request #509 from ministryofjustice/dependabot/pip/cachetools-3.1.0

Author: dependabot[bot]

requirements.txt

@@ -2,7 +2,7 @@ asn1crypto==0.24.0
 auth0-python==3.6.1
 boto3==1.9.86
 botocore==1.12.86
-cachetools==3.0.0
+cachetools==3.1.0
 certifi==2018.11.29
 cffi==1.11.5
 chardet==3.0.4