third_party: bump memtier version

ligurio · ligurio · commit 0310aa9f0cd0 · 2021-12-16T20:10:24.000+03:00
Many changes added since 2015, see [1]. 1. https://github.com/RedisLabs/memtier_benchmark/compare/40d47a0e..820605c7
diff --git a/third_party/memtier b/third_party/memtier
@@ -1 +1 @@
-Subproject commit 40d47a0e3b84b14e2ca88d9f0d506b4f04e39b16
+Subproject commit 820605c79f19fd165e3a31dddc89a9b465ccd459
