src/xxHash: bump xxHash submodule to enable RISC-V RVV optimizations

Signed-off-by: Sun Yuechi <sunyuechi@iscas.ac.cn>

diff --git a/src/xxHash b/src/xxHash
index bbb27a5efb85b92a0486cf361a8635715a53f6ba..e573d4d2aaeaba0f3e5a0a9a54144a1f2b4b56e7 160000 (submodule)
--- a/src/xxHash
+++ b/src/xxHash
@@ -1 +1 @@
-Subproject commit bbb27a5efb85b92a0486cf361a8635715a53f6ba
+Subproject commit e573d4d2aaeaba0f3e5a0a9a54144a1f2b4b56e7