Bump version to 1.0.4

[martinkim0]

• Closes #xxxx (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest docs/release_notes/index.md file if fixing a bug or adding a new feature.
• If the changes are patches for a version, I have added the on-merge: backport to x.x.x label.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (70f5917) 89.12% compared to head (43d15fa) 89.17%.
Report is 2 commits behind head on main.

❗ Current head 43d15fa differs from pull request most recent head f18c7b3. Consider uploading reports for the commit f18c7b3 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2286      +/-   ##
==========================================
+ Coverage   89.12%   89.17%   +0.05%     
==========================================
  Files         145      145              
  Lines       11839    11839              
==========================================
+ Hits        10551    10557       +6     
+ Misses       1288     1282       -6     

Files	Coverage Δ
scvi/data/_datasets.py	85.18% <100.00%> (ø)

... and 6 files with indirect coverage changes

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