fix(pu): fix hppo entropy_weight to avoid nan error in log_prob

[puyuan1996]

Description

• fix hppo entropy_weight to avoid nan error in log_prob

Related Issue

• H-PPO算法运行失败 #760

TODO

Check List

• merge the latest version source branch/repo, and resolve all the conflicts
• pass style check
• pass all the tests

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (4d53074) 77.11% compared to head (2cae4d8) 77.10%.
Report is 3 commits behind head on main.

Files	Patch %	Lines
ding/policy/ppo.py	0.00%	1 Missing ⚠️
ding/rl_utils/td.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #761      +/-   ##
==========================================
- Coverage   77.11%   77.10%   -0.01%     
==========================================
  Files         671      671              
  Lines       53676    53776     +100     
==========================================
+ Hits        41394    41466      +72     
- Misses      12282    12310      +28     

Flag	Coverage Δ
unittests	77.10% <60.00%> (-0.01%)	⬇️

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