Add changelog about SomePostgreSqlException

Author: phadej

CHANGES.md

@@ -4,6 +4,9 @@
   * Use `postgresql-libpq >=0.10.0.0`. It includes critical fixes,
     by using `postgresql-simple >=0.7` you won't get older `postgresql-libpq`.
   * Drop support for GHC prior 8.6
+  * Added a class for `postgresql-simple` exceptions: `SomePostgreSqlException`.
+    This allows to catch all `postgresql-simple` exceptions at once.
+    (c.f. `AsyncException` in `base).
 
 ### Version 0.6.5.1 (2023-07-09)