Update mkdirp to avoid warnings on npm install

[ehmicky]

On npm install netlify-cli the following warning is shown:

npm WARN deprecated mkdirp@0.5.4: Legacy versions of mkdirp are no longer supported. Please update to mkdirp 1.x. (Note that the API surface has changed to use Promises in 1.x.)

This is due to the following dependencies:

$ npm ls mkdirp
netlify-cli@2.40.0 /home/ehmicky/.nvm/versions/node/v13.11.0/lib/node_modules/netlify-cli
├─┬ copy-template-dir@1.4.0
│ └── mkdirp@0.5.4  deduped
├─┬ gh-release-fetch@1.0.3
│ └── mkdirp@0.5.4  deduped
└── mkdirp@0.5.4

Fixing this problem would require:

• Upgrading mkdirp to latest version in Netlify CLI
• Upgrading mkdirp to latest version in netlify/gh-release-fetch
• Switching copy-template-dir to another library, since that one is not maintained anymore

Note: make-dir is an alternative that might be better maintained.

[RaeesBhatti]

Thanks for reporting this issue @ehmicky.

[RaeesBhatti]

Fixed in the latest version