update pyyaml requirement to 5.3.1

lbry/conf.py

@@ -5,9 +5,8 @@ import typing
 import logging
 from argparse import ArgumentParser
 from contextlib import contextmanager
-
-import yaml
 from appdirs import user_data_dir, user_config_dir
+import yaml
 from lbry.error import InvalidCurrencyError
 from lbry.dht import constants
 from lbry.wallet.coinselection import STRATEGIES
@@ -334,7 +333,7 @@ class ConfigFileAccess:
         cls = type(self.configuration)
         with open(self.path, 'r') as config_file:
             raw = config_file.read()
-        serialized = yaml.load(raw) or {}
+        serialized = yaml.safe_load(raw) or {}
         for key, value in serialized.items():
             attr = getattr(cls, key, None)
             if attr is None:

setup.py

@@ -46,7 +46,7 @@ setup(
         'msgpack==0.6.1',
         'prometheus_client==0.7.1',
         'ecdsa==0.13.3',
-        'pyyaml==4.2b1',
+        'pyyaml==5.3.1',
         'docopt==0.6.2',
         'hachoir',
         'multidict==4.6.1',