chore: exclude .NET metadata from UPM packages

.npmignore

@@ -10,3 +10,5 @@ DotNet~/
 Godot~/
 NuGet.Config
 Directory.Build.props
+NuGet.Config.meta
+Directory.Build.props.meta

Directory.Build.props.meta

@@ -1,2 +1,7 @@
 fileFormatVersion: 2
 guid: a7abc1d6a557c4d43b173af60b092a58
+DefaultImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

README.md.meta

@@ -1,2 +1,7 @@
 fileFormatVersion: 2
 guid: bdde8e9f7b07f284b913f8810caddad9
+TextScriptImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: