[enh] upgrade duniterpy dependency to 0.57.*

HeadV2 now get all properties from Head, HeadV0 and HeadV1

requirements.txt

@@ -2,7 +2,7 @@ aiohttp==3.6.2
 async-timeout==3.0.1
 asynctest==0.13.0
 attrs==19.3.0
-duniterpy==0.56.0
+duniterpy==0.57.*
 jsonschema==3.2.0
 networkx==2.4
 PyQt5==5.9.2

src/sakia/data/processors/nodes.py

@@ -152,14 +152,9 @@ class NodesProcessor:
                 logging.debug("Update node: {0}".format(head.pubkey[:5]))
                 node.previous_buid = node.current_buid
                 node.current_buid = head.blockstamp
-                # todo: https://git.duniter.org/clients/python/duniterpy/issues/120
                 # capture sofware and version
-                if isinstance(head, HeadV2):
-                    node.software = head.v1.software
-                    node.version = head.v1.software_version
-                else:
-                    node.software = head.software
-                    node.version = head.software_version
+                node.software = head.software
+                node.version = head.software_version
 
                 self._repo.update(node)
                 return node, True