Added .scale metadata-files to gitignore (#6130)

To prevent [similar
issues](https://github.com/paritytech/polkadot-sdk/pull/6124) add .scale
files to gitignore

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

.gitignore

@@ -40,3 +40,4 @@ rls*.log
 runtime/wasm/target/
 substrate.code-workspace
 target/
+*.scale