Fix bogus date in RPM changelog

3 jobs from bogus-date in 6 minutes and 23 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #8970
build_bionic

00:02:58

passed #8969
build_stretch

00:03:09

 
  Sign
failed #8971
sign

00:00:15

 
Name Stage Failure
failed
sign Sign
$ ci-sign-pkg
========================================================================
=
= Configure and check
=
declare -x CI_COMMIT_REF_NAME="bogus-date"
declare -- RESULT_DIR="result"
ci-sign-pkg: use GPG_PRIVATE_KEY (runner) or GPG_USER_ID (workstation)
ERROR: Job failed: exit code 1