Hover style for right sidebar avatars has wrong border color
### Summary
The avatars in the right sidebar seem to use the wrong hover border-color.
### Example Project
-> This issue on the right sidebar.
### What is the current *bug* behavior?
Hover color is `rgba(245, 245, 245, 0.2)`
### What is the expected *correct* behavior?
Hover color should be something like `rgb(220,220,200)`
### Relevant screenshots
| Normal | Hover | Explanation |
| ------ | ----- | ----------- |
|  |  | (assignee icon) The normal color of the border is `#F5F5F5`, hover color: `rgba(245,245,245,0.2)` |
|  |  | (project icon) The normal color of the border is `#F5F5F5`, hover color: `#DCDCDC` |
### Possible fixes
1. Within `.right-sidebar a:not(.btn-retry):hover .avatar`: `border-color: rgba(245,245,245,0.2) -> $avatar-border-hover`
2. Additionally within `.avatar &:not([href]):hover`: `border-color: darken($avatar-border, 10%) -> $avatar-border-hover`
issue