Some personal sites forget to put <meta name="go-import" ...> in a
<head> element, so look anywhere for them.
Partly fixes <https://issues.guix.gnu.org/50595>.
Reported by Stephen Paul Weber <singpolyma@singpolyma.net>.
* guix/import/go.scm (fetch-module-meta-data): Match "go-import" meta
tags anywhere in the page.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>