Fix experimental usage error (#687)

It is okay to use experimental annotations, if it is in the same module.

iOS can't be built without suppressing this warning:
https://teamcity.jetbrains.com/buildConfiguration/JetBrainsPublicProjects_Compose_BuildNativeForPullRequests/4232288?hideProblemsFromDependencies=false&hideTestsFromDependencies=false&expandPull+Request+Details=true&expandBuildProblemsSection=true&expandBuildChangesSection=true

compose/material3/material3/build.gradle

@@ -166,6 +166,10 @@ if(AndroidXComposePlugin.isMultiplatformEnabled(project)) {
                 implementation(libs.junit)
                 implementation(libs.skikoCurrentOs)
             }
+
+            configureEach {
+                languageSettings.optIn("androidx.compose.material3.ExperimentalMaterial3Api")
+            }
         }
     }
 }