Fix pull request check images

[BasThomas]

Sometimes, GitHub seems to supply us with the wrong image / user / actor when dealing with status checks. See here.

We should report this to GitHub and check the results after.

As seen in #1530, the Bitrise check should use the Bitrise avatar / image, not Ryan's.

[rnystrom]

Filed

[BasThomas]

The heck, that URL redirects to the forum overview? 👎

[j-f1]

Seems like the post disappeared 🤷‍♂️