Update webext-sdk dependency to 0.8.0

Background / User story

In order to enable extensions to upgrade to EWE 0.8.0, we need to update the dependency here first, without breaking any integration that still relies on older SDK versions.

Dependency changes

• Name: webext-sdk
• New version: 0.8.0
• Breaking changes: None.
• Other changes:
  • https://gitlab.com/eyeo/adblockplus/abc/webext-sdk/-/issues/343 - "circumvention"-type filter list are being updated dynamically.
  • https://gitlab.com/eyeo/adblockplus/abc/webext-sdk/-/issues/404 - Added regex filter support.

Integration changes

• Legal: TBD
• Development: Update the dependency.

Hints for testers

We are no longer fetching/storing/building "circumvention"-type filter lists, as those are updated dynamically by EWE 0.8.