fix(deps): update minor and patch for gatsby-source-contentful

[wardpeet]

This PR contains the following updates:

Package	Type	Update	Change
axios	dependencies	minor	^0.19.2 -> ^0.20.0

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Release Notes

axios/axios

### [`v0.20.0`](https://togithub.com/axios/axios/blob/master/CHANGELOG.md#​0200-August-20-2020) [Compare Source](https://togithub.com/axios/axios/compare/v0.19.2...v0.20.0) Release of 0.20.0-pre as a full release with no other changes.

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