upgrade acceptable rdflib version

Author: mr-c

requirements.txt

@@ -1,8 +1,8 @@
 requests>=2.4.3
 ruamel.yaml>=0.12.4,<=0.16.5
-rdflib>=4.2.2,<4.3
+rdflib>=4.2.2,<5.1
 shellescape>=3.4.1,<3.5
-schema-salad>=7,<8
+schema-salad>=7.0.20210124093443,<8
 prov==1.5.1
 bagit==1.6.4
 mypy-extensions

setup.py

@@ -95,9 +95,9 @@
         "requests >= 2.6.1",  # >= 2.6.1 to workaround
         # https://github.com/ionrock/cachecontrol/issues/137
         "ruamel.yaml >= 0.12.4, <= 0.16.5",
-        "rdflib >= 4.2.2, < 4.3.0",
+        "rdflib >= 4.2.2, < 5.1.0",
         "shellescape >= 3.4.1, < 3.5",
-        "schema-salad >= 7, < 8",
+        "schema-salad >= 7.0.20210124093443, < 8",
         "mypy-extensions",
         "psutil",
         "prov == 1.5.1",