Merge pull request #310 from DE-RSE/add-rse-day-2025-uni-hh

Add RSE Day 2025 at University Hamburg to events

Author: led02

_includes/events/2025.md

@@ -4,5 +4,6 @@
 | S3C | 2025-05-05 - 2025-05-08 | Denver, CO | [S3C](https://s3c.sandia.gov/) | Sustainable Scientific Software Conference (S3C) |
 | Nordic-RSE 2025 | 2025-05-20 - 2025-05-21 | Gothenburg, Sweden | [Nordic-RSE 2025](https://nordic-rse.org/nrse2025/) | |
 | RSEHPC\@ISC25 | 2025-06-13 | Hamburg | [RSEHPC\@ISC25](https://www.helmholtz-hirse.de/events/2025_06_13-rsehpcatisc.html) | co-located with [ISC25](https://web.archive.org/web/20250127091253/https://isc-hpc.com/) |
+| RSE Day 2025 Universität Hamburg | 2025-07-16 | Hamburg | https://www.hcds.uni-hamburg.de/news/2025/20250502-rse-day.html | |
 | RSECon25 | 2025-09-09 - 2025-09-11 | Warwick, UK | [RSECon25](https://rsecon25.society-rse.org/) | |
 | US-RSE'25 | 2025-10-06 - 2025-10-08 | Philadelphia, USA | [US-RSE'25](https://us-rse.org/usrse25/) | |