qprep: commit LMDB transaction on SIGINT

Closes #17
5 jobs for qprep-handle-sigint in 1 minute and 25 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #142173
docker linux amd64
test:flake8

00:00:14

passed #142172
docker linux amd64
test:mypy

00:00:18

passed #142174
docker linux amd64
test:pylint

00:00:22

passed #142175
docker linux amd64
test:pytest

00:00:16

passed #142176
docker linux amd64
test:respdiff

00:01:23