fix avatar stretched on 1:1 call

[I-lander]

Fixes https://github.com/element-hq/element-web/issues/27427

In a 1:1 private conversation with another person, when receiving a call, the avatar icon is stretch :

As it is:

As it should be:

The issue is due to the flex box of the parent element > mx_IncomingLegacyCallToast As there is no align-item property, the elements can be strectched.

To test:

1. Call anybody in a 1:1 room

Signed-off-by: I-lander [email protected]

[I-lander]

@florianduros I signed off :)

[I-lander]

Thank you for your contribution. I tested the change and it is working.

We need you to sign-off your contribution.

I signed off the pr