version 10.0 is not compatible with typescript

**Steps:**

1. Upgrade from 9.2.1 to 10.0.0 or 10.0.1
3. Typescript compilation fails:
```
error TS2688: Cannot find type definition file for 'long'.
The file is in the program because:
Entry point for implicit type library 'long'
```

Expect upgrading to v10 shouldn't fail compile.

**Cause:**

Version 10.0 depends on google-gax 5.0.2-rc.1, which includes dependency @types/long ^5.0.0

This dependency is deprecated and was removed in [google-gax latest version 5.0.1](https://github.com/googleapis/gax-nodejs/releases/tag/google-gax-v5.0.1)

**Resolution:**

Changing dependency google-gax version to non-rc 5.0.1 or later (latest 5.0.3) resolves the Typescript compile error.