style: Apply ruff/flake8-simplify rule SIM118

SIM118 Use `key in dict` instead of `key in dict.keys()`

Author: DimitriPapadopoulos

tests/common.py

@@ -101,7 +101,7 @@ def unregister_test_codecs():
 
 
 def is_test_codec(codec):
-    return codec in test_codec_infos.keys()
+    return codec in test_codec_infos
 
 
 def built_in_equivalent_of_test_codec(test_codec):

tests/test_cli.py

@@ -891,7 +891,7 @@ def test_valid_encodings(self):
         }
 
         with temp_workspace(workspace):
-            for config_path in config_files.keys():
+            for config_path in config_files:
                 # First, make sure that encoding autodetection works when the
                 # file’s path is given as a command-line argument.
                 with RunContext(self) as ctx: