Remove tests for .peek

Author: lizmat

S17-concurrency/channel.t

@@ -1,16 +1,14 @@
 use v6;
 use Test;
 
-plan 14;
+plan 12;
 
 {
     my $c = Channel.new;
     $c.send(1);
     $c.send(2);
-    is $c.peek, 1, "Peeked first value";
     is $c.receive, 1, "Received first value";
     is $c.poll, 2, "Polled for second value";
-    ok $c.peek === Nil, "peek returns Nil when no values available";
     ok $c.poll === Nil, "poll returns Nil when no values available";
 }