enable support for foss 2025b in EESSI version 2025.06

Author: bedroge

eb_hooks.py

@@ -63,6 +63,7 @@
     '2025.06': [
         {'name': 'foss', 'version': '2024a'},
         {'name': 'foss', 'version': '2025a'},
+        {'name': 'foss', 'version': '2025b'},
     ],
 }