update changelog for v0.13.13

Author: schmalliso

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+* Update GitHub actions by @i80and in https://github.com/mongodb/snooty-parser/pull/424
+* DOP-3159: README overhaul by @seungpark in https://github.com/mongodb/snooty-parser/pull/425
+* DOP-3307: Generate metadata for OpenAPI content pages by @rayangler in https://github.com/mongodb/snooty-parser/pull/426
+* DOP-3353: Change OpenAPI metadata source to be spec string by @rayangler in https://github.com/mongodb/snooty-parser/pull/428
+
 ## [v0.13.12] - 2022-10-19
 
 ### Fixed