Fetch tags in Github workflows

[reuterbal]

Small bugfix PR: The GH workflows did not fetch tags in the clone, therefore the Loki version number was always wrong (including in the published docs).

[github-actions[bot]]

Documentation for this branch can be viewed at https://sites.ecmwf.int/docs/loki/305/index.html

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.97%. Comparing base (0e011a0) to head (e9b4bca).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #305 +/- ## ======================================= Coverage 94.97% 94.97% ======================================= Files 151 151 Lines 32407 32407 ======================================= Hits 30779 30779 Misses 1628 1628 ``` | [Flag](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/305/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | Coverage Δ | | |---|---|---| | [lint_rules](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/305/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | `96.39% <ø> (ø)` | | | [loki](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/305/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | `95.13% <ø> (ø)` | | | [transformations](https://app.codecov.io/gh/ecmwf-ifs/loki/pull/305/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs) | `92.17% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf-ifs#carryforward-flags-in-the-pull-request-comment) to find out more.

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