FIX: Change URL to release tag

[maxulysse]

Change URL to the release tag

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

[mirpedrol]

We will need to make the same change in the linting test multiqc_config.py https://github.com/nf-core/tools/blob/master/nf_core/lint/multiqc_config.py#L78

[codecov]

Codecov Report

Merging #2412 (6b20a81) into dev (ba395fe) will decrease coverage by 0.17%.
Report is 16 commits behind head on dev.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev    #2412      +/-   ##
==========================================
- Coverage   71.23%   71.07%   -0.17%     
==========================================
  Files          87       87              
  Lines        9415     9431      +16     
==========================================
- Hits         6707     6703       -4     
- Misses       2708     2728      +20     

Files Changed	Coverage Δ
nf_core/lint/multiqc_config.py	67.79% <ø> (ø)

... and 2 files with indirect coverage changes