Exclude test images from cargo package

Cargo.toml

@@ -14,6 +14,7 @@ authors = [
 license = "MIT"
 description = "TIFF decoding and encoding library in pure Rust"
 repository = "https://github.com/image-rs/image-tiff"
+exclude = ["tests/images/*", "tests/fuzz_images/*"]
 
 [dependencies]
 byteorder = "1.2"