build(deps): update fixtures requirement from >=2.0 to >=4.3.2

Updates the requirements on [fixtures](https://github.com/testing-cabal/fixtures) to permit the latest version.
- [Changelog](https://github.com/testing-cabal/fixtures/blob/master/NEWS)
- [Commits](testing-cabal/fixtures@2.0.0...4.3.2)

---
updated-dependencies:
- dependency-name: fixtures
  dependency-version: 4.3.2
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -1 +1 @@
-fixtures>=2.0
+fixtures>=4.3.2