adjust to new schema_salad version

Author: mr-c

requirements.txt

@@ -2,7 +2,7 @@ requests>=2.4.3
 ruamel.yaml>=0.12.4,<=0.15.77
 rdflib>=4.2.2,<4.3
 shellescape>=3.4.1,<3.5
-schema-salad>=2.8,<3
+schema-salad>=3.0,<3.1
 typing>=3.5.3; python_version<"3.6"
 pathlib2==2.3.2; python_version<"3"
 prov==1.5.1

setup.py

@@ -53,7 +53,7 @@
           'ruamel.yaml >= 0.12.4, <= 0.15.77',
           'rdflib >= 4.2.2, < 4.3.0',
           'shellescape >= 3.4.1, < 3.5',
-          'schema-salad >= 2.8, < 3',
+          'schema-salad >= 3.0, < 3.1',
           'mypy-extensions',
           'six >= 1.9.0',  # >= 1.9.0 required by prov
           'psutil',