[unity] Added missing TextureRegion.meta file. Closes #2060.

spine-csharp/src/TextureRegion.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 17b4075f6e1d4e5478f4730c2f4cc54d
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: