react should be a peerDependency

[ehaynes99]

Currently, react is listed as a dependency. This causes a second version of react to be installed as a dependency of this one, appearing under `node_modules.

$ npm ls react
react-excel-renderer-test@0.1.0 /path/to/project
└─┬ react-excel-renderer@1.1.0
  └── react@16.13.1

$ ls node_modules/react-excel-renderer/node_modules/
react

As this library is already assuming the consuming app uses react, it should be a peer dependency, using the version of react already installed, which would look something like:

$ npm ls react
react-excel-renderer-test@0.1.0 /path/to/project
└── react@16.13.1

$ ls node_modules/react-excel-renderer/node_modules
ls: node_modules/react-excel-renderer/node_modules: No such file or directory