build(deps): bump github.com/cloudevents/sdk-go/v2

Bumps [github.com/cloudevents/sdk-go/v2](https://github.com/cloudevents/sdk-go) from 2.12.0 to 2.15.0.
- [Release notes](https://github.com/cloudevents/sdk-go/releases)
- [Commits](cloudevents/sdk-go@v2.12.0...v2.15.0)

---
updated-dependencies:
- dependency-name: github.com/cloudevents/sdk-go/v2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

benchmarks/chained-function-eventing/go.mod

@@ -5,7 +5,7 @@ go 1.21
 replace github.com/vhive-serverless/vSwarm/tools/benchmarking_eventing => ../../tools/benchmarking_eventing
 
 require (
-	github.com/cloudevents/sdk-go/v2 v2.12.0
+	github.com/cloudevents/sdk-go/v2 v2.15.0
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/vhive-serverless/vSwarm/tools/benchmarking_eventing v0.0.0-00010101000000-000000000000
 	google.golang.org/grpc v1.60.0

benchmarks/chained-function-eventing/go.sum

@@ -1,7 +1,7 @@
 github.com/benbjohnson/clock v1.1.0 h1:Q92kusRqC1XV2MjkWETPvjJVqKetz1OzxZB7mHJLju8=
 github.com/benbjohnson/clock v1.1.0/go.mod h1:J11/hYXuz8f4ySSvYwY0FKfm+ezbsZBKZxNJlLklBHA=
-github.com/cloudevents/sdk-go/v2 v2.12.0 h1:p1k+ysVOZtNiXfijnwB3WqZNA3y2cGOiKQygWkUHCEI=
-github.com/cloudevents/sdk-go/v2 v2.12.0/go.mod h1:xDmKfzNjM8gBvjaF8ijFjM1VYOVUEeUfapHMUX1T5To=
+github.com/cloudevents/sdk-go/v2 v2.15.0 h1:aKnhLQhyoJXqEECQdOIZnbZ9VupqlidE6hedugDGr+I=
+github.com/cloudevents/sdk-go/v2 v2.15.0/go.mod h1:lL7kSWAE/V8VI4Wh0jbL2v/jvqsm6tjmaQBSvxcv4uE=
 github.com/containerd/containerd v1.6.26 h1:VVfrE6ZpyisvB1fzoY8Vkiq4sy+i5oF4uk7zu03RaHs=
 github.com/containerd/containerd v1.6.26/go.mod h1:I4TRdsdoo5MlKob5khDJS2EPT1l1oMNaE2MBm6FrwxM=
 github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=