2.4.0 Relationship loading, filtering improvements, fixes

What's Changed

• pass request to data layer by @mahenzon in #61
• fix loading multi relationships by @mahenzon in #59
• Fix type cast in filters by @CosmoV in #62
• Fix null value filtering by @CosmoV in #60
• add py.typed by @mahenzon in #64
• limit view methods by @mahenzon in #63
• bump version to 2.4.0 by @mahenzon in #65

Full Changelog: 2.3.2...2.4.0