Update rdoc requirement from ~> 2.4 to ~> 3.12

[dependabot]

Updates the requirements on rdoc to permit the latest version.

Changelog

Sourced from rdoc's changelog.

=== 3.12.1 / 2013-02-05

• Bug fixes
  • Fixed an XSS exploit in darkfish.js. This could lead to cookie disclosure
    to third parties. See CVE-2013-0256[rdoc-ref:CVE-2013-0256.rdoc] for full
    details including a patch you can apply to generated RDoc documentation.
  • Ensured that rd parser files are generated before checking the manifest.

=== 3.12 / 2011-12-15

• Minor enhancements

  • Added DEVELOPERS document which contains an overview of how RDoc works and
    how to add new features to RDoc.
  • Improved title for HTML output to include --title in the
    title element.
  • rdoc --pipe now understands --markup.
  • RDoc now supports IRC-scheme hyperlinks. Issue #83 by trans.

• Bug fixes

  • Fixed title on HTML output for pages.
  • Fixed parsing of non-indented HEREDOC.
  • Fixed parsing of %w[] and other % literals. Issue #84 by
    Erik Hollensbe
  • Fixed arrow replacement in HTML output munging the spaceship operator.
    Issue #85 by eclectic923.
  • Verbatim sections with ERB that match the ruby code whitelist are no
    longer syntax-highlighted. Issue #86 by eclectic923
  • Line endings on windows are normalized immediately after reading with
    binmode. Issue #87 by Usa Nakamura
  • RDoc better understands directives for comments. Comment directives can
    now be found anywhere in multi-line comments. Issue #90 by Ryan Davis
  • Tidy links to methods show the label again. Issue #88 by Simon Chiang
  • RDoc::Parser::C can now find comments directly above
    +rb_define_class_under+. Issue #89 by Enrico
  • In rdoc, backspace and ansi formatters, labels and notes without bodies
    are now shown.
  • In rdoc, backspace and ansi formatters, whitespace between label or note
    and the colon is now stripped.

=== 3.11 / 2011-10-17

• Bug fixes
  • Avoid parsing TAGS files included in gems. Issue #81 by Santiago
    Pastorino.

=== 3.10 / 2011-10-08

• Major enhancements
  • RDoc HTML output has been improved:
    • The search from Володя Колесников's (Vladimir Kolesnikov) SDoc has been

... (truncated)

Commits

• See full diff in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot ignore this [patch|minor|major] version will close this PR and stop Dependabot creating any more for this minor/major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language

You can disable automated security fix PRs for this repo from the Security Alerts page.