refactor(constants): add google language option zh

deep_translator/constants.py

@@ -25,6 +25,7 @@ GOOGLE_CODES_TO_LANGUAGES = {
     'ca': 'catalan',
     'ceb': 'cebuano',
     'ny': 'chichewa',
+    'zh': 'chinese (simplified)',
     'zh-cn': 'chinese (simplified)',
     'zh-tw': 'chinese (traditional)',
     'co': 'corsican',
@@ -158,7 +159,7 @@ LINGUEE_LANGUAGES_TO_CODES = {
     "hungarian": "hu",
     "romanian": "ro",
     "russian": "ru",
-    #"serbian": "sr",
+    # "serbian": "sr",
     "dutch": "nl",
     "slovakian": "sk",
     "greek": "el",
@@ -169,7 +170,7 @@ LINGUEE_LANGUAGES_TO_CODES = {
     "finnish": "fi",
     "chinese": "zh",
     "french": "fr",
-    #"croatian": "hr",
+    # "croatian": "hr",
     "czech": "cs",
     "laotian": "lo",
     "swedish": "sv",