Auto merge of #3411 - Matt-Gleich:master, r=Turbo87

🍱 Crop favicon

Hello! At first glance I found crates.io's favicon to be a bit small compared to other site's favicons. Looked into it and found that the logo hasn't been cropped. All I did was crop the favicon in this PR. As you can see from the image below (new favicon on the right) it looks much better:

![Screen Shot 2021-03-13 at 11 53 09 PM](https://user-images.githubusercontent.com/43759105/111057675-46379100-8457-11eb-881e-1268f922fc36.jpg)

Thank you, maintainers! :)

Author: bors