[http_multi_server] Prepare to release 3.2.3 (#2028)

pkgs/http_multi_server/CHANGELOG.md

diff --git a/pkgs/http_multi_server/CHANGELOG.md b/pkgs/http_multi_server/CHANGELOG.md
index 362ed64..8809550 100644
--- a/pkgs/http_multi_server/CHANGELOG.md
+++ b/pkgs/http_multi_server/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 3.2.3-wip
+## 3.2.3
 
 * Fix `HttpMultiServer.loopback(0)` failing without retrying when the allocated
   IPv4 ephemeral port is already bound on `[::1]` in the same process.

pkgs/http_multi_server/pubspec.yaml

diff --git a/pkgs/http_multi_server/pubspec.yaml b/pkgs/http_multi_server/pubspec.yaml
index 26b7e21..eab5b7c 100644
--- a/pkgs/http_multi_server/pubspec.yaml
+++ b/pkgs/http_multi_server/pubspec.yaml
@@ -1,5 +1,5 @@
 name: http_multi_server
-version: 3.2.3-wip
+version: 3.2.3
 description: >-
   A dart:io HttpServer wrapper that handles requests from multiple servers.
 repository: https://github.com/dart-lang/http/tree/master/pkgs/http_multi_server