bread-onnx: fix workspace test build with load-dynamic dev-dependency

cargo test --workspace failed to link bread-onnx's own unit tests
(undefined symbol OrtGetApiBase) because nothing in this workspace
supplies an ort backend — that's deliberately left to each downstream
consumer app (breadarr, breadmill, breadpad) in their own repos. None
of bread-onnx's unit tests actually open an ONNX session, so enabling
ort's load-dynamic feature as a dev-dependency (unifies into this
crate's own test builds only, never into downstream consumers) is
enough to satisfy the linker without requiring a real onnxruntime.

Cargo.lock

@@ -1337,6 +1337,16 @@ version = "0.2.186"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66"
 
+[[package]]
+name = "libloading"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "754ca22de805bb5744484a5b151a9e1a8e837d5dc232c2d7d8c2e3492edc8b60"
+dependencies = [
+ "cfg-if",
+ "windows-link",
+]
+
 [[package]]
 name = "libredox"
 version = "0.1.18"
@@ -1563,6 +1573,7 @@ version = "2.0.0-rc.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d7de3af33d24a745ffb8fab904b13478438d1cd52868e6f17735ef6e1f8bf133"
 dependencies = [
+ "libloading",
  "ndarray",
  "ort-sys",
  "smallvec",