update conditional interceptor tests

Author: MathieuTricoire

Tests/GRPCCoreTests/Call/ConditionalInterceptorTests.swift

@@ -48,7 +48,9 @@ struct ConditionalInterceptorTests {
         [.fooBar, .fooBaz, .barFoo]
       ),
       (
-        .allMatching { descriptor in descriptor.method == "baz" },
+        .allMatching { (_ descriptor: MethodDescriptor) -> Bool in
+          descriptor.method == "baz"
+        },
         [.fooBaz, .barBaz],
         [.fooBar, .barFoo]
       ),