chore: Mark flaky test in A2AServerJsonRpcIntegrationTest as @disabled

Author: kpavlov

a2a/a2a-server/src/jvmTest/kotlin/ai/koog/a2a/server/jsonrpc/A2AServerJsonRpcIntegrationTest.kt

@@ -26,6 +26,7 @@ import kotlinx.coroutines.test.runTest
 import kotlinx.coroutines.withContext
 import org.junit.jupiter.api.AfterAll
 import org.junit.jupiter.api.BeforeAll
+import org.junit.jupiter.api.Disabled
 import org.junit.jupiter.api.TestInstance
 import org.junit.jupiter.api.parallel.Execution
 import org.junit.jupiter.api.parallel.ExecutionMode
@@ -43,6 +44,7 @@ import kotlin.uuid.Uuid
 @OptIn(ExperimentalUuidApi::class)
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 @Execution(ExecutionMode.SAME_THREAD)
+@
 class A2AServerJsonRpcIntegrationTest : BaseA2AServerJsonRpcTest() {
     override val testTimeout = 10.seconds
 
@@ -78,6 +80,7 @@ class A2AServerJsonRpcIntegrationTest : BaseA2AServerJsonRpcTest() {
         super.`test send message streaming`()
 
     @Test
+    @Disabled("Flaky test, needs investigation")
     override fun `test get task`() =
         super.`test get task`()