Fix: to_dict returns wrong enum fields when numbering is not consecutive (#102)

Fixes #93 to_dict returns wrong enum fields when numbering is not consecutive

tests/inputs/config.py

@@ -5,7 +5,7 @@ xfail = {
     "namespace_keywords",  # 70
     "namespace_builtin_types",  # 53
     "googletypes_struct",  # 9
-    "googletypes_value",  # 9,
+    "googletypes_value",  # 9
     "import_capitalized_package",
     "example",  # This is the example in the readme. Not a test.
 }