fix: use the closed window in the eof response

[vaibhavtiwari33]

Based off of numaproj/numaflow-rs#177

[codecov]

Codecov Report

❌ Patch coverage is 91.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.72%. Comparing base (e3d3afd) to head (21bb66b).

Files with missing lines	Patch %	Lines
...kages/pynumaflow/pynumaflow/accumulator/_dtypes.py	75.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #360      +/-   ##
==========================================
- Coverage   92.74%   92.72%   -0.03%     
==========================================
  Files          67       67              
  Lines        3514     3531      +17     
  Branches      228      230       +2     
==========================================
+ Hits         3259     3274      +15     
- Misses        190      191       +1     
- Partials       65       66       +1     

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.