root: bump wire pin to latest upstream HEAD
Move the ocaml-wire pin from a84e4992b5 to 5185e50fe across every opam
file and template, and refresh the generated 3d under it. This does not
yet make the C agree harnesses for codecs whose type names contain
underscores compile: the new wire still mangles e.g. Grpc_message to
Grpcmessage in the agree generator while EverParse (and the committed
wrappers) use GrpcMessage, so the validator names mismatch. That needs an
everparse_name fix upstream in wire; fat and btree (no underscores in
their type names) are unaffected and their agree corpora still pass.