fix assert in pit.py

[StalkerShurik]

What does this PR do?

Fixes #<issue_number>

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

---

📚 Documentation preview 📚: https://torchmetrics--2811.org.readthedocs.build/en/2811/

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 35%. Comparing base (0a19c47) to head (cd5688f).
Report is 1 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (0a19c47) and HEAD (cd5688f). Click for more details.

HEAD has 60 uploads less than BASE

Flag	BASE (0a19c47)	HEAD (cd5688f)
torch2.0.1+cpu	6	3
python3.10	18	9
Windows	4	2
cpu	28	14
Linux	18	9
python3.8	2	1
torch2.5.0+cpu	2	1
python3.12	6	3
macOS	6	3
torch2.5.0	2	1
torch2.0.1	4	2
torch2.2.2+cpu	2	1
torch2.3.1+cpu	2	1
torch2.1.2+cpu	2	1
python3.11	2	1
torch2.4.1+cu121	4	2
torch2.5.0+cu124	4	2
gpu	2	0
unittest	2	0

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2811     +/-   ##
========================================
- Coverage      69%     35%    -34%     
========================================
  Files         340     326     -14     
  Lines       18448   18277    -171     
========================================
- Hits        12679    6311   -6368     
- Misses       5769   11966   +6197