Bump pyyaml from 5.1 to 5.4 in /committee/mock_availability_gateway

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.1 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@5.1...5.4)

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

Author: dependabot[bot]

committee/mock_availability_gateway/setup.py

@@ -16,7 +16,7 @@
     packages=find_packages(),
     install_requires=[
         'aiohttp==3.6.2',
-        'PyYAML==5.1',
+        'PyYAML==5.4',
         'Web3==5.2.2',
     ],
     package_data={