PostgreSQL：type double does not exist

#### 问题描述及重现代码：

```c#
模型：
public sealed class TestStoreModel
{
public long Id { get; set; }
[Column(DbType = "double precision")]
}
表：
CREATE TABLE IF NOT EXISTS "public"."TestData" (
"Id" BIGINT DEFAULT 0,
"Double" DOUBLE PRECISION DEFAULT 0 NOT NULL,
CONSTRAINT "public_TestData_pkey" PRIMARY KEY ("Id")
) WITH (OIDS=FALSE);
freesql 执行 await freesql.Insert(new TestStoreModel
{
Id = YitIdHelper.NextId(),
Double = 2.718281828459,
}).ExecuteAffrowsAsync(token); 时报错：42704: type "double" does not exist
```

#### 数据库版本
PostgreSQL 11.10 on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit

#### 安装的Nuget包
FreeSql.Provider.PostgreSQL 3.5.311

#### .net framework/. net core？ 及具体版本
dotnet10

Start by reproducing the shown TestStoreModel insert with FreeSql.Provider.PostgreSQL against PostgreSQL 11.10, then trace the provider's handling of the [Column(DbType = "double precision")] mapping. Done means the insert succeeds without the `type "double" does not exist` error and a regression test covers this mapping.

Written by the indexing model from the issue text.