Make test_create_decode_mask more specific by validating only m2g edges

[zweihuehner]

Describe your changes

Updated test_create_decode_mask to check only m2g (decoding) edges, not total edges. This is done by individually checking the edge components.

Focusing the test on m2g edges ensures it only checks the intended effect of the decode mask, making it independent of edge connectivity of g2m or m2m that might also use decode_mask in the future.

Issue Link

Solves #103

Type of change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📖 Documentation (Addition or improvements to documentation)

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[Copilot]

Pull request overview

Refines the decode-mask regression test to assert on the intended graph component (m2g decoding edges) rather than total edge count, making the test more future-proof as other components evolve.

Changes:

• Update test_create_decode_mask to count only m2g edges when validating filtering behavior.
• Adjust the test’s description to match the new, more specific assertion.
• Add a changelog entry describing the test change.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
tests/test_graph_creation.py	Narrows the decode-mask assertion to m2g edges by filtering edges via the component attribute.
CHANGELOG.md	Notes the test refinement under Unreleased changes.

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