Add downstream ci

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (80087e9) 94.94% compared to head (6d1c2da) 94.96%. Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #68 +/- ## ========================================== + Coverage 94.94% 94.96% +0.02% ========================================== Files 16 16 Lines 1700 1707 +7 Branches 210 210 ========================================== + Hits 1614 1621 +7 Misses 66 66 Partials 20 20 ``` | [Files](https://app.codecov.io/gh/ecmwf/pdbufr/pull/68?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf) | Coverage Δ | | |---|---|---| | [tests/test\_40\_sample\_data.py](https://app.codecov.io/gh/ecmwf/pdbufr/pull/68?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ecmwf#diff-dGVzdHMvdGVzdF80MF9zYW1wbGVfZGF0YS5weQ==) | `98.91% <100.00%> (+0.02%)` | :arrow_up: |

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[FussyDuck]

All committers have signed the CLA.

[iainrussell]

Hi Sandor, you can merge this in now!