Bump pyyaml from 5.3.1 to 5.4 in /collection_manager

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)

---
updated-dependencies:
- dependency-name: pyyaml
  dependency-type: direct:production
...

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

Author: dependabot[bot]

collection_manager/requirements.txt

@@ -1,4 +1,4 @@
-PyYAML==5.3.1
+PyYAML==5.4
 pystache==0.5.4
 pysolr==3.9.0
 watchdog==0.10.2