HTTP Method is wrong

Python 3.6
http-parser 0.8.3

```python
from http_parser.http import HttpStream, HTTP_REQUEST
from io import BytesIO

stream = HttpStream(BytesIO(b"GET /admin HTTP/1.1\r\n\r\n"), kind=HTTP_REQUEST)
```

This will raise AssertError

```python
assert stream.method() == "GET" # DELETE
assert stream.url() == "/admin"
```
This is correct

```python
assert stream.url() == "/admin"
assert stream.method() == "GET"
```

首先使用 http-parser 0.8.3 运行提供的 Python 3.6 复现代码，并检查 HttpStream.method() 如何处理请求行。确认对于所示输入，该方法被报告为 GET，同时 stream.url() 仍为 /admin；断言通过后，issue 即完成。

由索引模型根据 Issue 内容生成。