build(deps): bump pyyaml from 5.3.1 to 5.4 in /tests

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.3.1 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@5.3.1...5.4)

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

tests/setup.py

@@ -13,7 +13,7 @@
     package_data={'': ['*.md']},
     include_package_data=True,
     install_requires=[
-        'ducktape==0.8.0', 'prometheus-client==0.9.0', 'pyyaml==5.3.1'
+        'ducktape==0.8.0', 'prometheus-client==0.9.0', 'pyyaml==5.4'
     ],
     scripts=[],
 )