You must have a "bareword" to the left of the arrow for the autoquoting to work, and "content-type" is not a bareword. Fortunately, LWP permits an underscore to be used in a header name, and automatically changes the underscore to a dash, so rewrite your invocation as:

    my $res = $ua->request(POST $url, 
                           content_type  => 'form-data', 
                           content       => $query, 
                           authorization => "Basic " . AUTHORISATION, 
                          );
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and you should be fine.

-- Randal L. Schwartz, Perl hacker