Adding 2025 placeholder with date/time.

Author: sei-smcmillan

hpec_bof.md

@@ -10,6 +10,12 @@ The GraphBLAS Forum members and anyone else is invited to attend this
 meeting that occurs every year in September at the [IEEE High Performance
 Extreme Computing (HPEC) Conference](https://ieee-hpec.org/).
 
+## 2025 Schedule
+
+When: 5:30-7:30PM EDT Tuesday, September 16.
+
+Schedule TBD
+
 ## 2024 Schedule
 
 When: 5:30-7:30PM EDT Tuesday, September 24.