docs(release): update changelog for the v3.1.0 release (#15959)

* update abi dumps

Author: scotthart

CHANGELOG.md

@@ -4,6 +4,13 @@
 breaking changes in the upcoming 4.x release. This release is scheduled for
 2027-12 or 2028-01.
 
+## v3.1.0 - 2026-02
+
+### Default Retry Policy Changes
+
+All libraries except Bigtable, PubSub, Spanner, and Storage have had their
+default maximum retry policy duration reduced from 30 minutes to 10 minutes.
+
 ## v3.0.0 - 2026-02
 
 **BREAKING CHANGES**

CMakeLists.txt

@@ -21,7 +21,7 @@ set(PACKAGE_BUGREPORT "https://github.com/googleapis/google-cloud-cpp/issues")
 
 project(
     google-cloud-cpp
-    VERSION 3.0.0
+    VERSION 3.1.0
     LANGUAGES CXX)
 set(PROJECT_VERSION_PRE_RELEASE "")
 

MODULE.bazel

@@ -16,7 +16,7 @@
 
 module(
     name = "google_cloud_cpp",
-    version = "3.0.0",  # Updated by CMake
+    version = "3.1.0",  # Updated by CMake
     compatibility_level = 3,  # Updated by CMake
 )