未抓取到埋点请求，一个断裂的gif文件

我们在基于anyproxy二次开发，自定义解析校验一些请求数据，
一些埋点数据通过 post 请求一个gif图，请求body携带 埋点信息，然而 anyproxy未抓取到该埋点访问
你可以尝试下抓改网站：https://www.sensorsdata.cn/
这个埋点上报请求未被抓取到 https://sensorswww.datasink.sensorsdata.cn/sa.gif?token=6b551cb59b1c1973

Plese fill the template when you reporting a new issue, thanks!

#### Which platform are you running AnyProxy

Mac
#### The version of the AnyProxy

4.1.3
#### Your expected behavior of AnyProxy

抓取到post请求的gif文件的请求body信息
#### The actual behavior of AnyProxy

对 post .gif 的请求未抓取到

Reproduce the missing POST .gif capture with AnyProxy 4.1.3 on macOS using the SensorsData URL in the report. Trace the request-capture path for that request type and compare it with other captured POST requests. Done means the proxy captures the request body for the reported tracking request.

Written by the indexing model from the issue text.