Add BUILD type to release note script (#5707)

Add BUILD type to automatic release notes script because it was missing.

---
TYPE: NO_HISTORY
DESC: Add BUILD type to release note script

Author: ypatia

scripts/parse_pr.py

@@ -10,6 +10,7 @@
     "FORMAT": "## Disk Format",
     "BREAKING_API": "## Breaking C API changes",
     "BREAKING_BEHAVIOR": "## Breaking behavior",
+    "BUILD": "## Build system changes",
     "FEATURE": "## New features",
     "IMPROVEMENT": "## Improvements",
     "DEPRECATION": "## Deprecations",