build: Attempt to fix build issues with current PyYAML build failure

Use of PyYAML 5.3.1 (was 5.4.1)

Author: Alan Christie

requirements.txt

@@ -3,4 +3,6 @@ im-data-manager-job-decoder == 1.17.1
 munch == 2.5.0
 yamllint == 1.30.0
 
-pyyaml >= 5.4.1, < 6.0.0
+# Docker compose limits us to PyYAML 5.x
+# Cython 3 issues (20 Jul) prevent us from using PyYAML 5.4.1
+pyyaml == 5.3.1