Assign RUSTSEC-2020-0002 to prost

Original PR: #222

Author: tarcieri

crates/prost/RUSTSEC-0000-0000.toml crates/prost/RUSTSEC-2020-0002.toml

@@ -1,5 +1,5 @@
 [advisory]
-id = "RUSTSEC-0000-0000"
+id = "RUSTSEC-2020-0002"
 package = "prost"
 date = "2020-01-16"
 title = "Parsing a specially crafted message can result in a stack overflow"