Bump pyyaml from 5.3.1 to 5.4 in /GardenPi

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>

GardenPi/requirements.txt

@@ -10,7 +10,7 @@ mysql-connector-python==8.0.21
 mysqlclient==2.0.1
 PyMySQL==0.10.0
 pyserial==3.4
-PyYAML==5.3.1
+PyYAML==5.4
 RPi.GPIO==0.7.0
 Werkzeug==1.0.1
 WTForms==2.3.3