changes APIHandler attribute "dump" to "header" for clarity

tests/chained_requests.py

@@ -9,13 +9,13 @@ class Header:
         '''Init method, apikey suggested but not required (empty by default).'''
         self.auth = {"Authorization" : apikey}
         self.content = {"Content-Type" : "application/json"}
-        self.dump = {**self.auth, **self.content}
+        self.header = {**self.auth, **self.content}
 
 def get_entry_from_elabid(elabid, entryType="items"):
     '''
     Function which returns entrypoint data (as dictionary) from its elabid.
     '''
-    header = Header(apikey).dump
+    header = Header(apikey).header
     response = requests.get(
         headers = header,
         url = f"{ELABFTW_API_URL}/{entryType}/{elabid}",