Don't remember about qiime but you can use reformat.sh from BBMap suite to do the conversion easily.

reformat.sh in=file.fq.gz out=file.fa

You can also use SeqKit:

seqkit fq2fa file.fq.gz -o file.fa

or even awk:

zcat file.fq.gz | awk 'NR%4=="1" || NR%4=="2" {gsub("^@", ">", $0); print $0}' > file.fa