dependencies: ginkgo v2.15.0, gomega v1.31.0

The main reason for updating is support for reporting the cause of context
cancellation: Ginkgo provides that information when canceling a context and
Gomega polling code includes that when generating a failure message.

vendor/github.com/onsi/gomega/internal/async_assertion.go

@@ -553,7 +553,12 @@ func (assertion *AsyncAssertion) match(matcher types.GomegaMatcher, desiredMatch
 				lock.Unlock()
 			}
 		case <-contextDone:
-			fail("Context was cancelled")
+			err := context.Cause(assertion.ctx)
+			if err != nil && err != context.Canceled {
+				fail(fmt.Sprintf("Context was cancelled (cause: %s)", err))
+			} else {
+				fail("Context was cancelled")
+			}
 			return false
 		case <-timeout:
 			if assertion.asyncType == AsyncAssertionTypeEventually {