fix(integration): fix FlaskIntegration for Werkzeug > 2.1.0

[michielderoos]

As explained in this bug report, recent versions of werkzeug introduced the behaviour to get_json where it will throw an error when content_type isn't set.

[cc-jj]

Fixes: #1936

[antonpirker]

So in old Werkzeug doing .get_json() never resulted in an error and now an error will be thrown unless you add .get_json(silent=True) which then makes get_json behave like in the old Werkzeug? Is this correct?

[michielderoos]

So in old Werkzeug doing .get_json() never resulted in an error and now an error will be thrown unless you add .get_json(silent=True) which then makes get_json behave like in the old Werkzeug? Is this correct?

@antonpirker Yes, exactly correct! And this is backwards compatible with old versions of Werkzeug as well, silent=true isn't new with their breaking change.