update changelog

CHANGES.txt

@@ -1,30 +1,23 @@
-Unreleased Changes (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
-
-  PHP
-  * Fix building packaged PHP extension (#9727)
-  * Fixed composer.json to only advertise compatibility with PHP 7.0+.  (#9819)
-
-  Ruby
-  * Disable the aarch64 build on macOS until it can be fixed. (#9816)
-
-  Other
-  * Fix versioning issues in 3.20.0
+2022-05-10 version 21.0-rc1 (C++/Java/Python/PHP/Objective-C/C#/Ruby)
 
   C++
+  * Rename main cmake/CMakeLists.txt to CMakeLists.txt (#9603)
+  * avoid allocating memory if all extension are cleared (#9345)
+  * cmake: Call get_filename_component() with DIRECTORY mode instead of PATH mode (#9614)
+  * Escape GetObject macro inside protoc-generated code (#9739)
+  * Update CMake configuration to add a dependency on Abseil (#9793)
+  * Use __constinit only in GCC 12.2 and up (#9936)
   * Refactor generated message class layout
   * Optimize tokenizer ParseInteger by removing division
   * Reserve exactly the right amount of capacity in ExtensionSet::MergeFrom
   * Parse FLT_MAX correctly when represented in JSON
 
-  Compiler
-  * Protoc outputs the list of suggested field numbers when invalid field
-    numbers are specified in the .proto file.
-  * Require package names to be less than 512 bytes in length
-
   Java
+  * Update protobuf_version.bzl to separate protoc and per-language java … (#9900)
   * 6x speedup in ArrayEncoder.writeUInt32NotTag
 
   Python
+  * Increment python major version to 4 in version.json for python upb (#9926)
   * The C extension module for Python has been rewritten to use the upb library.
     This is expected to deliver significant performance benefits, especially when
     parsing large payloads.  There are some minor breaking changes, but these
@@ -34,6 +27,40 @@ Unreleased Changes (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
     has been incremented.
   * The binary wheel for macOS now supports Apple silicon.
 
+
+  PHP
+  * chore: [PHP] fix phpdoc for MapField keys (#9536)
+  * [PHP] Remove unnecessary zval initialization (#9600)
+  * [PHP] fix PHP build system (#9571)
+  * Fix building packaged PHP extension (#9727)
+  * fix: reserve "ReadOnly" keyword for PHP 8.1 and add compatibility (#9633)
+  * fix: phpdoc syntax for repeatedfield parameters (#9784)
+  * fix: phpdoc for repeatedfield (#9783)
+  * Change enum string name for reserved words (#9780)
+  * Fixed composer.json to only advertise compatibility with PHP 7.0+.  (#9819)
+
+  Ruby
+  * Allow pre-compiled binaries for ruby 3.1.0 (#9566)
+  * Implement `respond_to?` in RubyMessage (#9677)
+  * [Ruby] Fix RepeatedField#last, #first inconsistencies (#9722)
+  * Do not use range based UTF-8 validation in truffleruby (#9769)
+  * Improve range handling logic of `RepeatedField` (#9799)
+  * Disable the aarch64 build on macOS until it can be fixed. (#9816)
+
+  Other
+  * [Kotlin] remove redundant public modifiers for compiled code (#9642)
+  * [C#] Update GetExtension to support getting typed value (#9655)
+  * Fix invalid dependency manifest when using `descriptor_set_out` (#9647)
+  * Fix C# generator handling of a field named "none" in a oneof (#9636)
+  * Add initial version.json file for 21-dev (#9840)
+  * Remove duplicate java generated code (#9909)
+  * Fix versioning issues in 3.20.0
+
+  Compiler
+  * Protoc outputs the list of suggested field numbers when invalid field
+    numbers are specified in the .proto file.
+  * Require package names to be less than 512 bytes in length
+
 2022-04-21 version 3.20.1 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
 
   PHP