Update .npmignore (#1862)

INTERNAL
Ignore other packages (nodegl, react-native) in the mono-repo when publishing tfjs-core.

Author: dsmilkov

.npmignore

@@ -1,8 +1,13 @@
+# Ignore other packages in the mono-repo.
+tfjs-webgpu/
+tfjs-backend-nodegl/
+tfjs-react-native/
+
 .vscode/
 .rpt2_cache/
 src/**/*_test.ts
 integration_tests/
-tfjs-webgpu/
+
 dist/backends/**/*_test.js
 models/
 coverage/