Change the path to `ICON.png`
Previously it didn't show on crates.io.
> `teloxide-core` versions less that `0.4.5` (`teloxide` versions less than 0.7.3) have a low-severity security vulnerability, [learn more >>](https://github.com/teloxide/teloxide/discussions/574)
<div align="center">
- <img src="ICON.png" width="250"/>
+ <img src="../../raw/master/ICON.png" width="250"/>
<h1>teloxide</h1>
<a href="https://docs.rs/teloxide/">
<img src="https://docs.rs/teloxide/badge.svg">
