Allow whitespace in duration strings and update tests

https://github.com/python-discord/bot/issues/446

After review feedback and a discussion in the dev-core team, I've
changed a couple of things:

- Allow a space between amount and unit in the duration string;

- Allow a space between different units in the duration string;

- Remove the old ExpirationDate converter completely;

- Remove the dependency `dateparser` from the Pipfile;

- Update tests for the two types of optional spaces;

- Change the test for valid cases to a more readable format;

This PR closes #446

1 files changed, 0 insertions, 1 deletions

diff --git a/Pipfile b/Pipfile
index 6a58054c1..33f44e9a6 100644
--- a/Pipfile
+++ b/Pipfile
@@ -17,7 +17,6 @@ aio-pika = "*"
 python-dateutil = "*"
 deepdiff = "*"
 requests = "*"
-dateparser = "*"
 more_itertools = "~=7.2"
 urllib3 = ">=1.24.2,<1.25"