[9.x] Make assertDatabaseHas failureDescription more multibyte charac…

[nshiro]

When assertDatabaseHas test fails, it shows you similar or found results.
While it's helpful, sometimes it can be difficult to see for those using multibyte languages.

This PR solves that problem.

sample test

    /** @test */
    function dbtest()
    {
        User::factory()->create([
            'name' => '名無しの権兵衛',
            'email' => '太郎@example.net'
        ]);

        $this->assertDatabaseHas(User::class, [
            'name' => '名無しの権兵衛',
            'email' => '次郎@example.net'
        ]);
    }

Before

After

This is a small addition, yet it helps us a lot.
Thank you always.