lupdate does not support trailing commas in Python

Python allows trailing commas inside function calls, and in particular the Black code reformatter adds these trailing commas when breaking long calls up over multiple lines. This is a particular problem for calls to translate(), which are often lengthy. What comes out of Black is something like:

translate(
    "AddonsInstaller",
    "Unable to read data from GitHub: check your internet connection and proxy settings and try again.",
)

lupdate does not extract this string, because upon seeing the comma after the text, it assumes there will then be a comment. When none is found, it acts as though it is a syntax error and stops the extraction for that line. I believe the same is true if there is a comment but no pluralization.

The problematic line is currently https://code.qt.io/cgit/qt/qttools.git/tree/src/linguist/lupdate/python.cpp#n519

// look for comment
if (!match(Tok_Comma) || !matchStringOrNone(comment))
    return false;

The logic at currently written is that if there is a comma, there must also be a comment, and if not the extraction failed.