Limit how many db backups to keep in s3

Let's go with 90 days worth.

Author: simonbaird

ansible/inventory.yml

@@ -29,6 +29,6 @@ all:
     # S3 backup configuration
     s3_backup_enabled: true
     s3_backup_bucket: "tiddlyhost-backups"
-    s3_backup_retention_days: 0
+    s3_backup_retention_days: 90
 
     prerelease_empty: https://tiddlywiki.com/prerelease/empty.html