xmllint (and Python's xml.etree) both pedantically complain about the
XML declaration not being at the start of the file:
$ xmllint /var/lib/flatpak/exports/share/metainfo/com.retrodev.blastem.appdata.xml
/var/lib/flatpak/exports/share/metainfo/com.retrodev.blastem.appdata.xml:2: parser error : XML declaration allowed only at the start of the document
xmllint (and Python's xml.etree) both pedantically complain about the XML declaration not being at the start of the file:
Fix this by moving the comment one line lower.