Inter 4.0. Fix `font-inter.rb`

[nikitabarskov]

For some reason for InterVariable.ttf and InterVariable-Italic.ttf have been prefixed with a wrong path. This commit fixes that.

• [ ] brew cask audit --download {{cask_file}} is error-free.

brew cask audit --download font-inter.rb
Error: `brew cask` is no longer a `brew` command. Use `brew <command> --cask` instead

• [ ] brew cask style --fix {{cask_file}} reports no offenses.

$ brew style --cask --fix font-inter.rb
font-inter.rb:51:3: C: FormulaAudit/Test: test do should not be empty
  test do ...
  ^^^^^^^
font-inter.rb:51:3: W: Lint/EmptyBlock: Empty block detected.
  test do ...
  ^^^^^^^

1 file inspected, 2 offenses detected

Would love to fix that as well.

• [x] The commit message includes the cask’s name and version.

Additionally, if adding a new cask:

• [ ] Named the cask according to the token reference.
• [ ] brew cask install {{cask_file}} worked successfully.
• [ ] brew cask uninstall {{cask_file}} worked successfully.
• [ ] Checked there are no open pull requests for the same cask.
• [ ] Checked the cask was not already refused in closed issues.
• [ ] Checked the cask is submitted to the correct repo.

I do not add a new formula or cask.

[github-actions[bot]]

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