meson: add proper cereal dependency

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib4ee9663a6f9ca5c97cb0bbf8c60d344f7f6d1b4
diff --git a/subprojects/cereal.wrap b/subprojects/cereal.wrap
new file mode 100644
index 0000000..a4cb7ec
--- /dev/null
+++ b/subprojects/cereal.wrap
@@ -0,0 +1,4 @@
+[wrap-git]
+url = https://github.com/USCiLab/cereal.git
+revision = HEAD
+# need at least for C++20 fixes 3e4d1b84cab4891368d2179a61a7ba06a5693e7f