[Security] Bump django from 2.2.3 to 2.2.4

[dependabot-preview]

Bumps django from 2.2.3 to 2.2.4.

Commits

• 8687fbe [2.2.x] Bumped version for 2.2.4 release.
• cf694e6 [2.2.x] Fixed CVE-2019-14235 -- Fixed potential memory exhaustion in django.u...
• 4f5b58f [2.2.x] Fixed CVE-2019-14234 -- Protected JSONField/HStoreField key and index...
• e34f3c0 [2.2.x] Fixed CVE-2019-14233 -- Prevented excessive HTMLParser recursion in s...
• c328971 [2.2.X] Fixed CVE-2019-14232 -- Adjusted regex to avoid backtracking issues w...
• f9462f4 [2.2.x] Fixed #30656 -- Added QuerySet.bulk_update() to the database optimiza...
• b4139ed [2.2.x] Refs #30656 -- Reorganized bulk methods in the database optimization ...
• ea57c8a [2.2.x] Added stub release notes for security releases.
• 4d6449e [2.2.x] Fixed #30647 -- Fixed crash of autoreloader when extra directory cann...
• 61d4a15 [2.2.x] Fixed typo in docs/topics/http/sessions.txt.
• Additional commits viewable in compare view

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[dependabot-preview]

We've just been alerted that this update fixes a security vulnerability:

Sourced from The GitHub Security Advisory Database.

Moderate severity vulnerability that affects django
An issue was discovered in Django 1.11.x before 1.11.23, 2.1.x before 2.1.11, and 2.2.x before 2.2.4. If django.utils.text.Truncator's chars() and words() methods were passed the html=True argument, they were extremely slow to evaluate certain inputs due to a catastrophic backtracking vulnerability in a regular expression. The chars() and words() methods are used to implement the truncatechars_html and truncatewords_html template filters, which were thus vulnerable.

Affected versions: [">= 2.2.0, < 2.2.4"]