fix: Update generate-files.sh

Author: uncomputable

fuzz/generate-files.sh

@@ -27,8 +27,8 @@ path = "fuzz_lib/lib.rs"
 libfuzzer-sys = "0.4"
 # We shouldn't need an explicit version on the next line, but Andrew's tools
 # choke on it otherwise. See https://github.com/nix-community/crate2nix/issues/373
-simplicity-lang = { path = "..", features = ["test-utils"], version = "0.3.0" }
-old_simplicity = { package = "simplicity-lang", version = "0.3.0", default-features = false }
+simplicity-lang = { path = "..", features = ["test-utils"], version = "0.4.0" }
+old_simplicity = { package = "simplicity-lang", version = "0.3.1", default-features = false }
 
 [dev-dependencies]
 base64 = "0.22.1"