assume a textfile:

echo "import h from 'w.js?CACHEBUST';" > tmp/test.txt

this command:

sed -i 's/CACHEBUST/v=$(date +%s)/g' tmp/test.txt

results in my desired output:

import h from 'w.js?v=12345';

when trying to pipe that with find and xargs with:

find tmp -type f -print0 | xargs -0 sed -i 's/CACHEBUST/v=$(date +%s)/g'

I get undesired output:
import h from 'w.js?v=$(date +%s)';

My question: how do I force that expression to evaluate?