Bump slug from 6.0.0 to 7.0.0 in /backend

Created by: dependabot[bot]

Bumps slug from 6.0.0 to 7.0.0.

Changelog

Sourced from slug's changelog.

7.0.0 (2022-08-31)

chore

• drop support for Node.js 12.x and 17.x (#344) (a109d37)

BREAKING CHANGES

• Drop support for Node.js earlier than 14.x.

6.1.0 (2022-08-31)

Features

• add fallback option (#342) (b703043), closes #341

Commits

• d0bbee2 chore(release): 7.0.0 [skip ci]
• a109d37 chore: drop support for Node.js 12.x and 17.x (#344)
• 9f72c71 chore: update README (#343)
• b0a2809 chore(release): 6.1.0 [skip ci]
• b703043 feat: add fallback option (#342)
• d484b5b chore(deps-dev): bump semantic-release from 19.0.4 to 19.0.5
• c1e79a0 chore(deps-dev): bump semantic-release from 19.0.3 to 19.0.4
• 04567af chore: use ubuntu-latest in workflow
• 4bee7e6 chore: remove IE from karma config
• fb7e338 chore: update README to remove passed June 2022 date
• Additional commits viewable in compare view

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