Fixed issue with migrations on EFCore (xmin)

[micah686]

Renamed two column names on postgres.
Trying to run the server connecting to postgres:18-alpine results in migration errors, due to xmin being a system column name. Added an explicit column name to resolve this issue.

Here is the error message that it was creating before:

Unhandled exception. Npgsql.PostgresException (0x80004005): 42701: column name "xmin" conflicts with a system column name
   at Npgsql.Internal.NpgsqlConnector.ReadMessageLong(Boolean async, DataRowLoadingMode dataRowLoadingMode, Boolean readingNotifications, Boolean isReadingPrependedMessage)
   at System.Runtime.CompilerServices.PoolingAsyncValueTaskMethodBuilder`1.StateMachineBox`1.System.Threading.Tasks.Sources.IValueTaskSource<TResult>.GetResult(Int16 token)
   at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming, CancellationToken cancellationToken)
   at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming, CancellationToken cancellationToken)
   at Npgsql.NpgsqlDataReader.NextResult()
   at Npgsql.NpgsqlCommand.ExecuteReader(Boolean async, CommandBehavior behavior, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteReader(Boolean async, CommandBehavior behavior, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteNonQuery(Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteNonQuery()
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.Execute(IReadOnlyList`1 migrationCommands, IRelationalConnection connection, MigrationExecutionState executionState, Boolean beginTransaction, Boolean commitTransaction, Nullable`1 isolationLevel)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.<>c.<ExecuteNonQuery>b__3_1(DbContext _, ValueTuple`6 s)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IReadOnlyList`1 migrationCommands, IRelationalConnection connection, MigrationExecutionState executionState, Boolean commitTransaction, Nullable`1 isolationLevel)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.MigrateImplementation(DbContext context, String targetMigration, MigrationExecutionState state, Boolean useTransaction)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.<>c.<Migrate>b__20_1(DbContext c, ValueTuple`4 s)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.NpgsqlExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Npgsql.EntityFrameworkCore.PostgreSQL.Migrations.Internal.NpgsqlMigrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.Migrate(DatabaseFacade databaseFacade)
   at Valour.Server.Program.ConfigureServices(WebApplicationBuilder builder) in /home/micah/RiderProjects/Valour/Valour/Server/Program.cs:line 280
   at Valour.Server.Program.Main(String[] args) in /home/micah/RiderProjects/Valour/Valour/Server/Program.cs:line 81
   at Valour.Server.Program.<Main>(String[] args)
  Exception data:
    Severity: ERROR
    SqlState: 42701
    MessageText: column name "xmin" conflicts with a system column name
    File: heap.c
    Line: 479
    Routine: CheckAttributeNamesTypes
    ```

[SpikeViper]

IIRC we actually want it to be using xmin. I'll look into this - may need to tell it it doesn't have to generate the column.