Update reference to bib file

[xuanxu]

This PR updates the metadata of the paper source file to correctly reference the .bib file (string vs array).

Re: openjournals/joss-reviews#7313 (comment)

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[xuanxu]

• The JuBiotech maintainers know my real name.

At least one of the following two applies:

• The JuBiotech maintainers know my current employer.

• I am not making this contribution on behalf of my current employer.

[xuanxu]

I have read the CLA Document and I hereby sign the CLA.

[michaelosthege]

A YAML syntax problem. Of course. 🤐

Thanks a lot!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.19%. Comparing base (b48238a) to head (5fc6476).
Report is 140 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #44      +/-   ##
==========================================
+ Coverage   75.11%   75.19%   +0.08%     
==========================================
  Files           4        4              
  Lines         860      887      +27     
==========================================
+ Hits          646      667      +21     
- Misses        214      220       +6     

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