Update CHANGELOG and README for 3.3.1.

Author: ericproulx

CHANGELOG.md

@@ -8,9 +8,14 @@
 #### Fixes
 
 * [#2767](https://github.com/ruby-grape/grape/pull/2767): Update rubocop to 1.88.0 and rubocop-rspec to 3.10.2 - [@ericproulx](https://github.com/ericproulx).
+* Your contribution here.
+
+### 3.3.1 (2026-06-28)
+
+#### Fixes
+
 * [#2770](https://github.com/ruby-grape/grape/pull/2770): Avoid per-entry array allocation in `Request#build_headers` - [@ericproulx](https://github.com/ericproulx).
 * [#2771](https://github.com/ruby-grape/grape/pull/2771): Fix double wrap on json errors - [@MattHall](https://github.com/MattHall).
-* Your contribution here.
 
 ### 3.3.0 (2026-06-20)
 

README.md

@@ -11,7 +11,7 @@ Grape is a REST-like API framework for Ruby. It's designed to run on Rack or com
 ## Stable Release
 
 You're reading the documentation for the next release of Grape, which should be 4.0.0.
-The current stable release is [3.3.0](https://github.com/ruby-grape/grape/blob/v3.3.0/README.md).
+The current stable release is [3.3.1](https://github.com/ruby-grape/grape/blob/v3.3.1/README.md).
 
 ## Project Resources