[ci] Use proper env var for setting the git fetch depth
May fix errors such as in https://gitlab.opengeosys.org/ogs/ogs/-/pipelines/2916. See that the meta-job does not detect the last OGS tag.
May fix errors such as in https://gitlab.opengeosys.org/ogs/ogs/-/pipelines/2916. See that the meta-job does not detect the last OGS tag.