fix: replace removed readfp from configparser with read_file

Author: sbillinge

src/diffpy/srxconfutils/config.py

@@ -577,7 +577,7 @@ def parseConfigFile(self, filename):
                 self._copySelftoConfig()
                 fileobj = FakeConfigFile(filename)
                 # self.config.read(filename)
-                self.config.readfp(fileobj)
+                self.config.read_file(fileobj)
                 self._copyConfigtoSelf()
                 self._updateSelf()
         return