[main] Addressed certain issues with nullable DateTimeOffset values

[main] SelectMany with result selector is explicitly not supported when applied after grouping (like .GroupBy(groupingFunc).SelectMany(grouping, selector))

[main] Addressed issue of inability to delete column (including such on rename or change type via column recreation) because of undeleted foreign key

[main] Improved compatibility with non-windows runtimes

[main] Fixed inability to detect certain parameterizable parts within cached queries (Query.Execute()/.ExecuteDelayed()/ExecuteFuture() groups of methods)

[mysql] Fixed milliseconds extraction for DateTime expressions in queries

[mysql] Proper support for milliseconds v5.6+, already created columns will remain the same and new ones will have datetime(6) native type

[mysql] Improved compatibility with non-windows runtimes

[postgresql] For PostgreSQL 13+ apply 'trim_scale' function to results of aggregation to improve compatibility with .NET decimal

[postgresql] Improved compatibility with non-windows runtimes

[bulkoperations] Fixed certain cases of wrong update statements for Firebird provider

[reprocessing] Improved compatibility with non-windows runtimes