Debug state_graph

[Sichao25]

Bug description: The transition probability sum for some cell types is much larger than 1.

Proposed solution: Normalize the graph in state_graph() based on the number of target cell types for each trajectory found.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (1e8ffe4) 22.54% compared to head (d60f1a3) 22.17%.
Report is 166 commits behind head on master.

Files	Patch %	Lines
dynamo/prediction/state_graph.py	0.00%	1 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #630      +/-   ##
==========================================
- Coverage   22.54%   22.17%   -0.38%     
==========================================
  Files         166      166              
  Lines       27362    28032     +670     
==========================================
+ Hits         6168     6215      +47     
- Misses      21194    21817     +623     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.