Upgrade to net8 and EF8

[wallyrion]

Describe the change Upgrade target framework from net6 to net 8 Upgrade EF7 to EF8 for net8 framework

Tests All current tests pass, there shouldn't be a need for new tests. Only an additional target framework net8 added

Breaking change This is NOT backwards compatible with EF core 7 or lower.

Additional context

[wallyrion]

Looks like AppVeyor pipeline needs to be updated

[jamesbar2]

+1 For net8 and EF8 support

[knoxi]

+1 for .net 8