Add fuzzer found crash to corpus

test/core/json/corpus/crash-f21867fe8b6df0b54c13e2e6e613dce871ecf0f0

@@ -0,0 +1 @@
+ˆ)Ã!:{"*¾?'ʳ³!!*!à):!*à:::\udbD8ˆ)Ã!:{!`!?`¾¾!?'!*m,');…'`