Allow use of pypgstac loader within same major version.

[bitner]

Currently pypgstac requires that the version of pypgstac exactly matches the version of pgstac it is being used against. When using the loader we should allow the use of pypgstac that is the same minor version ie "v0.6.1" pypgstac should be able to still load data into a "v0.6.5" database but not a "v0.7.0" database.

Any breaking changes to how the pypgstac loader works would need to happen at a major release.