Update IGWN GitLab CI Templates to GitLab CI components

CI is returning errors like this:

$ ${PYTHON} -m coverage xml -o coverage-${CI_JOB_NAME_SLUG}.xml
$ # These components are deprecated # collapsed multi-line command
The IGWN GitLab CI Templates have been deprecated in favour of GitLab CI components.
The templates will no longer be supported by IGWN Computing and bugs are not likely to be fixed.
Please transition to using the new CI components. For more details, see
<https://computing.docs.ligo.org/guide/gitlab/components/>

Some insight into how to make this transition can probably be found in the Update to use CI/CD components MR from GLUE.