Update dependency ruby to v2.7.8

[renovate[bot]]

This PR contains the following updates:

Package	Update	Change
ruby (source)	minor	2.6.5 -> 2.7.8

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Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• [ ] If you want to rebase/retry this PR, check this box

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[renovate[bot]]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: Gemfile.lock

Fetching gem metadata from https://rubygems.org/...........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies......
Your bundle is locked to mimemagic (0.3.3), but that version could not be found
in any of the sources listed in your Gemfile. If you haven't changed sources,
that means the author of mimemagic (0.3.3) has removed it. You'll need to update
your bundle to a version other than mimemagic (0.3.3) that hasn't been removed
in order to install.