Fixes sqlalchemy#1273: Use "utf-8" encoding when reading conf file

Fix sqlalchemy#1273

This merge request explicitly sets the encoding of the configuration file being read to "utf-8" as recommended by https://docs.python.org/3/library/io.html#opt-in-encodingwarning

alembic/config.py

@@ -200,7 +200,7 @@ def file_config(self):
         self.config_args["here"] = here
         file_config = ConfigParser(self.config_args)
         if self.config_file_name:
-            file_config.read([self.config_file_name])
+            file_config.read([self.config_file_name], "utf-8")
         else:
             file_config.add_section(self.config_ini_section)
         return file_config