Make sure that only YYYYMMDD date directories are considered in glob when looking for run date

[morcuended]

We had a problem with the same run_id found in two different date directories. One of them was renamed Trash but it's still in the data directory. Therefore when looking for the date parent directory it is giving problems. Here I forced that only date directories with the correct format are considered.

[codecov]

Codecov Report

Merging #123 (6a71746) into main (98aefd1) will increase coverage by 0.01%.
The diff coverage is 92.30%.

@@            Coverage Diff             @@
##             main     #123      +/-   ##
==========================================
+ Coverage   82.23%   82.24%   +0.01%     
==========================================
  Files          51       51              
  Lines        4801     4811      +10     
==========================================
+ Hits         3948     3957       +9     
- Misses        853      854       +1     

Impacted Files	Coverage Δ
osa/tests/test_jobs.py	100.00% <ø> (ø)
osa/paths.py	86.32% <83.33%> (-0.41%)	⬇️
osa/conftest.py	91.52% <100.00%> (ø)
osa/tests/test_paths.py	100.00% <100.00%> (ø)

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