lib: don't read hidden files from the config directory

Fixes #104
7 jobs for wip/no-hidden-files in 2 minutes and 37 seconds (queued for 6 seconds)
Status Name Job ID Coverage
  Container
passed container_fedora #16043293

00:00:25

passed container_ubuntu #16043294

00:00:25

 
  Build
passed build_on_fedora_no_docs #16043296

00:01:22

passed build_on_fedora_with_docs #16043295

00:01:29

passed build_on_ubuntu_no_gir #16043298

00:01:21

passed build_on_ubuntu_with_gir #16043297

00:01:22

 
  Analysis
passed shellcheck #16043299

00:00:42