Bump pyyaml from 4.2b1 to 5.4 in /.circle

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 4.2b1 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](https://github.com/yaml/pyyaml/commits/5.4)

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

Author: dependabot[bot]

.circle/requirements.txt

@@ -1,3 +1,3 @@
 jsonschema==2.5.1
-pyyaml==4.2b1
+pyyaml==5.4
 requests[security]==2.21.0