Preparing for release, 3.3.0.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dblock

CHANGELOG.md

@@ -1,4 +1,4 @@
-### 3.3.0 (Next)
+### 3.3.0 (2026/10/09)
 
 * [#607](https://github.com/slack-ruby/slack-ruby-client/pull/607): Support non-rewindable Rack 3 request bodies when verifying Events API signatures, with WEBrick integration coverage; follows [#515](https://github.com/slack-ruby/slack-ruby-client/pull/515) - [@olleolleolle](https://github.com/olleolleolle), [@dblock](https://github.com/dblock).
 * [#606](https://github.com/slack-ruby/slack-ruby-client/pull/606): Add configured client copies with error callbacks for Slack and transport failures - [@dblock](https://github.com/dblock).
@@ -31,8 +31,6 @@
 * [#608](https://github.com/slack-ruby/slack-ruby-client/pull/608): Add admin.usergroups.addUsers, admin.usergroups.removeUsers, admin.usergroups.create, admin.usergroups.fetch, admin.usergroups.update, and admin.usergroups.uploadUsers methods - [@slack-ruby-ci-bot](https://github.com/apps/slack-ruby-ci-bot).
 * [#608](https://github.com/slack-ruby/slack-ruby-client/pull/608): Add canvases.getContent method to fetch canvas content as markdown or HTML - [@slack-ruby-ci-bot](https://github.com/apps/slack-ruby-ci-bot).
 * [#608](https://github.com/slack-ruby/slack-ruby-client/pull/608): Add new Slack API error codes to Errors - [@slack-ruby-ci-bot](https://github.com/apps/slack-ruby-ci-bot).
-* Your contribution here.
-
 ### 3.2.0 (2026/07/05)
 
 * [#581](https://github.com/slack-ruby/slack-ruby-client/pull/581): Migrate Danger to use danger-pr-comment workflow - [@dblock](https://github.com/dblock).

README.md

@@ -70,7 +70,7 @@ A Ruby client for the Slack [Web](https://api.slack.com/web) and [Events](https:
 
 ## Stable Release
 
-You're reading the documentation for the **next** release of slack-ruby-client. Please see the documentation for the [last stable release, v3.2.0](https://github.com/slack-ruby/slack-ruby-client/blob/v3.2.0/README.md) unless you're integrating with HEAD. See [UPGRADING](UPGRADING.md) when upgrading from an older version.
+You're reading the documentation for the **stable** release of slack-ruby-client, 3.3.0. See [UPGRADING](UPGRADING.md) when upgrading from an older version.
 
 ## Installation