golang-migrate无法找到postgres驱动程序

在我的 internal/platform/database/database.go

import (
    "github.com/golang-migrate/migrate"
    "github.com/jmoiron/sqlx"
    _ "github.com/lib/pq"
)

func RunMigrations() error {
    m, err := migrate.New(
        "file://schema",
        "postgres://postgres:postgres@localhost:5432/postgres?sslmode=disable")
    if err != nil {
        return errors.Wrap(err, "error creating migrations object")
    }

从我调用此函数cmd/my-api/main.go如下：

import (
    _ "github.com/golang-migrate/migrate/v4/database/postgres"
    _ "github.com/golang-migrate/migrate/v4/source/file"
    "github.com/jmoiron/sqlx"
    _ "github.com/lib/pq"
    "github.com/myrepo/myproject/internal/platform/database"
)

    // =========================================================================
    // Executing migrations
    if err := database.RunMigrations(); err != nil {
        log.Fatal(err)
    }

尽管我postgres在两个文件中都导入了驱动程序，_ "github.com/lib/pq"

运行该程序失败，如下所示：

error creating migrations object: source driver: unknown driver file (forgotten import?)
exit status 1

这是为什么？