[extractor/common] Fix _search_nuxt_data

[LowSuggestion912]

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Description of your pull request and other information

Fixes _search_nuxt_data incorrectly handling strings containing commas.

For example

webpage = '''
<script>
window.__NUXT__=(function(a,b){return
  {str1:a,str2:b}}("cool,string","lame string"));
</script>
'''

print(self._search_nuxt_data(webpage, None, traverse=None))

should produce
{'str1': 'cool,string', 'str2': 'lame string'}

instead of
{'str1': 'cool', 'str2': 'string'}

Template

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[Grub4K]

Good catch. The current result is even a bit more messed up, namely {'str1': '"cool', 'str2': 'string"'}