Gravatar resolution mismatch

[finga]

• Gitea version (or commit ref): 1.14.0-rc2, 1.14.0
• Git version: 2.20.1
• Operating system: Linux 4.19.0-14-amd64 Rename import paths: "github.com/gogits/gogs" -> "github.com/go-gitea/gitea" #1 SMP Debian 4.19.171-2 (2021-01-30) x86_64 GNU/Linux
• Binaries from: https://github.com/go-gitea/gitea/releases/download/
• Gitea is running with a systemd service file pretty similar to what is provided in the documentation, but on the default port with a nginx proxy infront.
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes https://try.gitea.io/test0r
  • No
• Log gist:

Description

The avatars sourced by gravatar have a too small resolution which results in a pixelated gravatar avatar. This behaviour is also reporducible on https://try.gitea.io.
After some investigation it seems as gitea queries the default gravatar size of 80x80 pixel. Which means that the 80x80 pixel avatar is expanded to 260x260px. A diff between the default gravatar image with size 80x80 pixel and the avatar delivered by gitea does not gather any difference between those two files.

Screenshots