test: add failing test to demonstrate potential bug

[ahey]

1. test complex calculation (AshPostgres.Test.ComplexCalculationsTest)
   test/complex_calculations_test.exs:5
   ** (RuntimeError) Error while building reference: latest_documentation_status
   code: |> AshPostgres.Test.ComplexCalculations.Api.load!([
   stacktrace:
   (ash_postgres 1.3.41) lib/expr.ex:846: AshPostgres.Expr.do_dynamic_expr/5
   (ash_postgres 1.3.41) lib/expr.ex:109: AshPostgres.Expr.do_dynamic_expr/5
   (ash_postgres 1.3.41) lib/expr.ex:356: AshPostgres.Expr.do_dynamic_expr/5
   (ash_postgres 1.3.41) lib/expr.ex:968: anonymous fn/6 in AshPostgres.Expr.do_dynamic_expr/5
   (ecto 3.10.3) lib/ecto/query/builder/dynamic.ex:76: Ecto.Query.Builder.Dynamic.expand/3
   (stdlib 5.0.2) lists.erl:1706: :lists.mapfoldl_1/3
   (elixir 1.15.4) lib/macro.ex:653: Macro.do_traverse/4
   (stdlib 5.0.2) lists.erl:1706: :lists.mapfoldl_1/3
   (stdlib 5.0.2) lists.erl:1707: :lists.mapfoldl_1/3
   (elixir 1.15.4) lib/macro.ex:653: Macro.do_traverse/4
   (stdlib 5.0.2) lists.erl:1706: :lists.mapfoldl_1/3
   (stdlib 5.0.2) lists.erl:1707: :lists.mapfoldl_1/3
   (elixir 1.15.4) lib/macro.ex:653: Macro.do_traverse/4
   (stdlib 5.0.2) lists.erl:1706: :lists.mapfoldl_1/3
   (elixir 1.15.4) lib/macro.ex:653: Macro.do_traverse/4
   (stdlib 5.0.2) lists.erl:1706: :lists.mapfoldl_1/3
   (elixir 1.15.4) lib/macro.ex:653: Macro.do_traverse/4
   (ecto 3.10.3) lib/ecto/query/builder/dynamic.ex:59: Ecto.Query.Builder.Dynamic.partially_expand/6
   (ecto 3.10.3) lib/ecto/query/builder/select.ex:235: Ecto.Query.Builder.Select.expand_nested/3
   (ecto 3.10.3) lib/ecto/query/builder/select.ex:274: Ecto.Query.Builder.Select.expand_nested_pair/3
   (elixir 1.15.4) lib/enum.ex:1825: anonymous fn/3 in Enum.map_reduce/3
   (stdlib 5.0.2) maps.erl:416: :maps.fold_1/4
   (elixir 1.15.4) lib/enum.ex:2522: Enum.map_reduce/3
   (ecto 3.10.3) lib/ecto/query/builder/select.ex:257: Ecto.Query.Builder.Select.expand_nested/3
   (ecto 3.10.3) lib/ecto/query/builder/select.ex:205: Ecto.Query.Builder.Select.select!/5
   (elixir 1.15.4) lib/enum.ex:2510: Enum."-reduce/3-lists^foldl/2-0-"/3
   (ash_postgres 1.3.41) lib/aggregate.ex:121: anonymous fn/6 in AshPostgres.Aggregate.add_aggregates/6
   (elixir 1.15.4) lib/enum.ex:4830: Enumerable.List.reduce/3
   (elixir 1.15.4) lib/enum.ex:2564: Enum.reduce_while/3
   (ash_postgres 1.3.41) lib/aggregate.ex:53: AshPostgres.Aggregate.add_aggregates/6
   (ash 2.13.3) lib/ash/query/aggregate.ex:570: anonymous fn/6 in Ash.Query.Aggregate.value_request/9
   (ash 2.13.3) lib/ash/engine/engine.ex:537: anonymous fn/2 in Ash.Engine.run_iteration/1
   (ash 2.13.3) lib/ash/engine/engine.ex:558: anonymous fn/4 in Ash.Engine.async/2
   (elixir 1.15.4) lib/task/supervised.ex:101: Task.Supervised.invoke_mfa/2
   (elixir 1.15.4) lib/task/supervised.ex:36: Task.Supervised.reply/4
   (ash 2.13.3) lib/ash/engine/engine.ex:552: Ash.Engine.async/2
   (elixir 1.15.4) lib/enum.ex:1693: Enum."-map/2-lists^map/1-1-"/2
   (elixir 1.15.4) lib/enum.ex:1693: Enum."-map/2-lists^map/1-1-"/2
   (ash 2.13.3) lib/ash/engine/engine.ex:702: Ash.Engine.start_pending_tasks/1
   (ash 2.13.3) lib/ash/engine/engine.ex:323: Ash.Engine.run_to_completion/1
   (ash 2.13.3) lib/ash/engine/engine.ex:252: Ash.Engine.do_run/2
   (ash 2.13.3) lib/ash/engine/engine.ex:148: Ash.Engine.run/2
   (ash 2.13.3) lib/ash/actions/read.ex:173: Ash.Actions.Read.do_run/3
   (ash 2.13.3) lib/ash/actions/read.ex:96: Ash.Actions.Read.run/3
   (ash 2.13.3) lib/ash/api/api.ex:1733: Ash.Api.load/4
   (ash 2.13.3) lib/ash/api/api.ex:1707: Ash.Api.load!/4
   test/complex_calculations_test.exs:55: (test)

[zachdaniel]

🚀 Thank you for your contribution! 🚀