It's -meta{} not meta().

While -meta is the recommended way of handling the majority of meta tags, current versions of CGI.pm (2.752+, possibly earlier) don't advocate it's use for generating HTTP-EQUIVs, instead saying...

To create an HTTP-EQUIV tag, use the -head argument as described below.

... and then under -head (reformatted for clarity) ...

To create an HTTP-EQUIV tag, use something like this:

      print start_html(
        -head => meta( {
          -http_equiv => 'Content-Type',
          -content    => 'text/html',
        } ),
      );
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    --k.

Update: Added CGI.pm version number.

Update II: On second glance, the current recommended method (ab)uses a feature in CGI's that turns any unknown CGI methods into (X)HTML...

$ perl -MCGI=foo -le 'print foo({-bar => "baz"})'
<FOO BAR="baz">
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