Add a CHANGELOG entry for version 1.4

Author: postgresql007

CHANGELOG

@@ -1,3 +1,20 @@
+Version 1.4, not yet released
+
+Bugfixes:
+- Match a literal underscore in the "pg\_%" LIKE pattern so that schemas
+  whose names merely start with "pg" (such as "pgabc123") are no longer
+  mistaken for system schemas and excluded from the views.
+
+Enhancements:
+- Add a containerised regression test harness (in "test/") that builds the
+  extension and runs "make installcheck" against PostgreSQL 12 through 19,
+  pulling not-yet-released versions from the pgdg-snapshot repository.
+- Add PostgreSQL 19 to the continuous integration matrix.
+- Expand the documentation with worked examples for every "*_permissions"
+  view, a walkthrough comparing the desired and actual state with
+  "permission_diffs()" and the updatable views, and a section relating the
+  extension to common compliance frameworks.
+
 Version 1.3, released 2024-06-12
 
 Enhancements: