submodule: bump up rapidjson submodule

to include the C++20 fixes introduced recently.

Signed-off-by: Kefu Chai <tchaikov@gmail.com>

diff --git a/src/rapidjson b/src/rapidjson
index f54b0e47a08782a6131cc3d60f94d038fa6e0a51..e4bde977440d4a00f820b6586899e48a972d2493 160000 (submodule)
--- a/src/rapidjson
+++ b/src/rapidjson
@@ -1 +1 @@
-Subproject commit f54b0e47a08782a6131cc3d60f94d038fa6e0a51
+Subproject commit e4bde977440d4a00f820b6586899e48a972d2493