Update changelog for 1.13.0 (#1837)

These things were not actually in CHANGELOG_PENDING, but it's probably
worth doing a release here since it's Wednesday, and a couple of things
have been updated.

Author: tgummerer

CHANGELOG.md

@@ -1,9 +1,19 @@
 CHANGELOG
 =========
 
+## 1.13.0
+
+### Improvements
+
+* Support parameterization in mocks
+
+* Update pulumi/pulumi dependencies
+
 ## 1.12.0
 
-- Allow --attach-debugger to attach to plugins
+### Improvements
+
+* Allow --attach-debugger to attach to plugins
 
 ## 1.11.0
 
@@ -623,4 +633,4 @@ CHANGELOG
 
 - [provider] Fix
   [#540](https://github.com/pulumi/pulumi-java/issues/540): language
-  host will no longer fail when doing plugin discovery
+  host will no longer fail when doing plugin discovery