fix(deps): update dependency webextension-polyfill to ^0.8.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
webextension-polyfill	^0.7.0 -> ^0.8.0

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Release Notes

mozilla/webextension-polyfill

### [`v0.8.0`](https://togithub.com/mozilla/webextension-polyfill/releases/0.8.0) [Compare Source](https://togithub.com/mozilla/webextension-polyfill/compare/0.7.0...0.8.0) ##### Bug Fixes - `browser.devtools.network.onRequestFinished` is now wrapped by the polyfill and provides a promise-based `request` API object ([#​250](https://togithub.com/mozilla/webextension-polyfill/pull/250), fixes [#​249](https://togithub.com/mozilla/webextension-polyfill/issues/249)) - the promise wrappers has been updated to reject with Error instances ([#​293](https://togithub.com/mozilla/webextension-polyfill/issues/293), fixes [#​257](https://togithub.com/mozilla/webextension-polyfill/issues/257)) See [all changes for 0.8.0](https://togithub.com/mozilla/webextension-polyfill/compare/0.7.0...0.8.0) - https://unpkg.com/webextension-polyfill@0.8.0/dist/

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