Fix bug in UDP checksum test

[JulianSchmid]

Closes #155

Summary by CodeRabbit

• Tests
  • Expanded automated CI test coverage by adding a new Linux big-endian target (linux-ppc64-stable) to the test matrix.
  • Adjusted CI test configuration to control PROPTEST_CASES per target, reducing iterations for emulated runs.
  • Improved UDP checksum-related test expectations for IPv4 and IPv6 scenarios to better validate checksum derivation.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds a Linux ppc64 stable CI test target, forwards PROPTEST_CASES into Cross for cross-compiled test runs, and removes .to_le() from five UDP checksum proptest cases.

Changes

CI and UDP test updates

Layer / File(s)	Summary
Add ppc64 cross-test target .github/workflows/main.yml, Cross.toml	Adds linux-ppc64-stable to the test matrix, includes a matching powerpc64-unknown-linux-gnu entry with reduced proptest cases, and passes PROPTEST_CASES through GitHub Actions and Cross.
Adjust UDP checksum proptests etherparse/src/transport/udp_header.rs	Removes .to_le() from sourceless_checksum calculations in five IPv4 and IPv6 checksum proptest cases.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title matches the main change: a fix in UDP checksum tests, including the checksum-related test adjustment.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch udp-big-endian-test-fix

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[coderabbitai]

🧹 Nitpick comments (1)

.github/workflows/main.yml (1)

10-101: 🔒 Security & Privacy | 🔵 Trivial | ⚡ Quick win

Consider adding an explicit permissions: block.

Static analysis flags the workflow as running with default (broad) GITHUB_TOKEN permissions since no permissions: block is defined. Scoping this down (e.g., contents: read) follows least-privilege practice for CI workflows.

🔒 Suggested addition

+permissions:
+  contents: read
+
 jobs:
   test:

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In @.github/workflows/main.yml around lines 10 - 101, The main workflow job in
main.yml is using the default broad GITHUB_TOKEN scope because no permissions
block is set. Add an explicit permissions configuration for the test job, scoped
to the minimum needed (for example, contents: read), near the test matrix job
definition so the CI runs with least-privilege access.

Source: Linters/SAST tools

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In @.github/workflows/main.yml:
- Around line 10-101: The main workflow job in main.yml is using the default
broad GITHUB_TOKEN scope because no permissions block is set. Add an explicit
permissions configuration for the test job, scoped to the minimum needed (for
example, contents: read), near the test matrix job definition so the CI runs
with least-privilege access.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 460bbd72-10d1-4516-892b-f5ebe07e50a2

📥 Commits

Reviewing files that changed from the base of the PR and between 73f1909 and fb6b52c.

📒 Files selected for processing (2)

• .github/workflows/main.yml
• Cross.toml

✅ Files skipped from review due to trivial changes (1)

• Cross.toml