Python dependency: Bump testtools from 2.8.2 to 2.8.4 in /web/regression

[dependabot]

Bumps testtools from 2.8.2 to 2.8.4.

Changelog

Sourced from testtools's changelog.

2.8.4

Improvements
------------
* Clear ``force_failure`` in ``_reset()`` so that re-running a test
  after an ``expectThat`` failure can succeed if successful conditions are met again.
  (OumarCamara, [#563](https://github.com/testing-cabal/testtools/issues/563))


Make extract_result() and DeferredNotFired public APIs in
testtools.twistedsupport. These utilities are useful for extracting
results from synchronous Deferreds in tests.
(Jelmer Vernooij, #546)


Add support for unittest.TestCase.subTest. Failures are reported
individually while the entire test method is still treated as a single test.
(Stephen Finucane, #567)


Add testtools.matchers.test module providing a test harness for
users who write their own custom matchers.
(Stephen Finucane)


Changes


Re-add compat helpers and helper modules that were accidentally removed
in a patch release, breaking API compatibility. These are now deprecated
and will be removed in a future major release.
(Stephen Finucane, #566)


typing-extensions is no longer required at runtime; it is only needed
for type checking.
(Jelmer Vernooij, Takashi Kajinami, #569, #571)


2.8.3

Changes

• Add 'Typing :: Typed' classifier to package metadata. (Jelmer Vernooij)

Improvements

• Add comprehensive type annotations to assertions, compat, run, and other modules. (Jelmer Vernooij, Stephen Finucane)

• Support async setUp/tearDown validation with Deferreds.

... (truncated)

Commits

• 8f3b59c release 2.8.4
• 0e24e95 Update NEWS
• 60f7126 Merge pull request #571 from testing-cabal/avoid-extensions
• 14ecca3 Avoid importing typing extensions unless type checking
• 53ec652 Merge pull request #566 from stephenfin/restore-compat-helpers
• 3665841 Add testtools.matchers.test module
• ec03064 Re-add helpers modules
• 2c5de4e Re-add removed compat helpers
• eca83db Merge pull request #570 from kajinamit/fix-569
• c582b4c Fix missing typing-extensions in Python < 3.11
• Additional commits viewable in compare view

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[dependabot]

Looks like testtools is up-to-date now, so this is no longer needed.