cppgc: Fix missing <algorithm> header

This fixes the gcov build.

Bug: chromium:1056170
Change-Id: I40ac42b6fce77367c6a366544abf89fc21075cdc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2228510
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Auto-Submit: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68125}

test/unittests/heap/cppgc/write-barrier-unittest.cc

@@ -4,6 +4,7 @@
 
 #include "include/cppgc/internal/write-barrier.h"
 
+#include <algorithm>
 #include <initializer_list>
 #include <vector>