Update dependency go to v1.25.1

Author: renovate[bot]

go.mod

@@ -2,7 +2,7 @@ module github.com/buildkite/elastic-ci-stack-for-aws/v6
 
 go 1.24.0
 
-toolchain go1.24.5
+toolchain go1.25.1
 
 require (
 	github.com/google/go-cmp v0.7.0