Update the configuration version for pyyaml

Signed-off-by: Chin Yeung Li <[email protected]>

Author: chinyeungli

etc/conf/base.txt

@@ -14,7 +14,7 @@ click==6.7
 # used by schematics
 six
 
-pyyaml==3.12
+PyYAML >= 3.0, < 4.0
 
 # license expression support
 license_expression

setup.py

@@ -70,7 +70,7 @@ def read(*names, **kwargs):
         'jinja2 >= 2.9, < 3.0',
         'click >= 6.7, < 7.0',
         "backports.csv ; python_version<'3.6'",
-        'pyyaml >= 3.11, < 3.13',
+        'PyYAML >= 3.0, < 4.0',
         'boolean.py >= 3.5, < 4.0',
         'license_expression >= 0.94, < 1.0',
     ],