[IpInfoDb] Update CHANGELOG.md

Author: jbelien

src/Provider/IpInfoDb/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 The change log describes what is "Added", "Removed", "Changed" or "Fixed" between each release.
 
+## 4.0.1
+
+### Fixed
+
+- Use `countryCode` from API
+
 ## 4.0.0
 
 First release of this library.