Bump rack from 2.2.6.2 to 2.2.6.4 (#9)

Bumps [rack](https://github.com/rack/rack) from 2.2.6.2 to 2.2.6.4.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/rack/rack/commit/27addc7f1ae290b6b84c1c351e5b6d75a05bb40b"><code>27addc7</code></a>
bump version</li>
<li><a
href="https://github.com/rack/rack/commit/ee7919ea04303717858be1c3f16b406adc6d8cff"><code>ee7919e</code></a>
Avoid ReDoS problem</li>
<li><a
href="https://github.com/rack/rack/commit/d6b5b2bab88f458fb048133604faebea952d8133"><code>d6b5b2b</code></a>
bump version</li>
<li><a
href="https://github.com/rack/rack/commit/9aac3757fe19cdb0476504c9245170115bec9668"><code>9aac375</code></a>
Limit all multipart parts, not just files</li>
<li>See full diff in <a
href="https://github.com/rack/rack/compare/v2.2.6.2...v2.2.6.4">compare
view</a></li>
</ul>
</details>
<br />


[![Dependabot compatibility
score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=rack&package-manager=bundler&previous-version=2.2.6.2&new-version=2.2.6.4)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

You can trigger a rebase of this PR by commenting `@dependabot rebase`.

[//]: # (dependabot-automerge-start)
[//]: # (dependabot-automerge-end)

---

<details>
<summary>Dependabot commands and options</summary>
<br />

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 close` will close this PR and stop Dependabot recreating
it. You can achieve the same result by closing it manually
- `@dependabot ignore this major version` will close this PR and stop
Dependabot creating any more for this major version (unless you reopen
the PR or upgrade to it yourself)
- `@dependabot ignore this minor version` will close this PR and stop
Dependabot creating any more for this minor 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](https://github.com/ackama/validate_html/network/alerts).

</details>

> **Note**
> Automatic rebases have been disabled on this pull request as it has
been open for over 30 days.

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -85,7 +85,7 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     racc (1.6.1)
-    rack (2.2.6.2)
+    rack (2.2.6.4)
     rack-test (2.0.2)
       rack (>= 1.3)
     rails-dom-testing (2.0.3)