Remove image link from ProbNum conference markdown

Removed image URL from the conference details.

Author: philipphennig

_meetings/2025_ProbNum.md

@@ -12,7 +12,7 @@ date_end: 2025-09-03
 summary: The first annual International Conference on Probabilistic Numerics.
 
 link: https://probnum25.github.io/
-img: https://probnum25.github.io/EURECOM-building-updated.jpg
+img: 
 img_caption: 
 
 url_code:
@@ -23,4 +23,4 @@ url_video:
 
 # More Information
 
-Find more information at [https://probnum25.github.io](https://probnum25.github.io).
+Find more information at [https://probnum25.github.io](https://probnum25.github.io).