Bump pyyaml from 3.11 to 5.4

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 3.11 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@3.11...5.4)

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

requirements.txt

@@ -4,8 +4,11 @@
 #
 #    pip-compile --output-file requirements.txt requirements.in
 #
-
-Jinja2==2.8
-MarkupSafe==0.23          # via jinja2
-PyYAML==3.11
+jinja2==2.8
+    # via -r requirements.in
+markupsafe==0.23
+    # via jinja2
+pyyaml==5.4
+    # via -r requirements.in
 six==1.10.0
+    # via -r requirements.in