Update pureHDF5 to v2.x

[jamaa]

Just a note before i forget it:
The used pureHDF5 Version should be updated for .NET 9.0. Currently we are using Versions 1.x because they supported .NET 4.8

Originally posted by @devmki in #228 (comment)

[jamaa]

wait until the update to .NET is complete

[jamaa]

@devmki the update to .NET has been merged to master now, would you like to create a pull request for updating the pureHDF5 package? I'm not sure if the test files in the Datasets repo are enough to ensure everything still works as intended.