fix: specify exact version in Cargo.toml (#40)

Author: tjdevries

bindings/rust/Cargo.toml

@@ -11,7 +11,7 @@ rust-version = "1.60.0"
 
 [dependencies]
 # Keep in sync with dev/proto-generate.sh
-protobuf = "3.0.2"
+protobuf = "=3.0.2"
 
 [lib]
 name = "rust"