fix: make JsonSerializable type alias read-only

[Pijukatel]

Bumping ty to 0.0.83 fails type-check: it rejects e.g. list[dict[str, int]] as JsonSerializable because list/dict are invariant.

Fix: JsonSerializable uses read-only Mapping/Sequence, so callers can keep passing plain dicts and lists. The alias is only used for inputs that get serialized.

The lock bumps only ty to 0.0.83 so CI proves the fix; unit tests pass; also clears the push_items error in apify-sdk-python.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.24%. Comparing base (77a3475) to head (c8126d2).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
src/apify_client/types.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1072      +/-   ##
==========================================
- Coverage   95.25%   95.24%   -0.02%     
==========================================
  Files          59       59              
  Lines        5547     5548       +1     
==========================================
  Hits         5284     5284              
- Misses        263      264       +1     

Flag	Coverage Δ
integration	92.05% <0.00%> (+0.19%)	⬆️
unit	87.40% <0.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ 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.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.