Add changelog entry for 0.14.3

Author: emillon

CHANGES.md

@@ -1,3 +1,15 @@
+### 0.14.3 (2020-07-22)
+
+#### Changes
+
+  + No functional changes from 0.14.2. The goal of this release is to be
+    compatible with base and stdio v0.14.0.
+
+  + Backport the following PRs:
+    - #1386 - Update opam metadata
+    - #1396 - Add compatibility with base.v0.14.0
+    - #1399 - Allow stdio.v0.14
+
 ### 0.14.2 (2020-05-11)
 
 #### Changes