Fix: Ensure Scope Filtering is Enforced Correctly

Resolves #1215

Purpose

This PR ensures that scope filtering logic is correctly applied when allowed_scopes is configured in ConventionalCommitParserOptions. Previously, commits without a scope were incorrectly bypassing the filtering, and commits with no allowed scopes defined were still being evaluated unnecessarily.

Rationale

1. If allowed_scopes is not defined, the filtering logic should be skipped entirely to maintain the existing behavior.
2. If allowed_scopes is defined, the commit must have a valid scope that is explicitly allowed.
3. If a commit has no scope, it should not be allowed when allowed_scopes is configured.

This change ensures a strict enforcement of scope filtering while keeping backwards compatibility when allowed_scopes is not set.

How did you test?

• Added unit tests to verify:

  • Commits with allowed scopes pass the filter.
  • Commits with disallowed scopes are correctly rejected.
  • Commits without a scope are rejected when allowed_scopes is enabled.
  • Commits without an allowed_scopes definition behave as they currently do.

• Ran the test suite and verified that existing functionality remains unchanged for users who do not configure scope filtering.

How to Verify

1. Run pytest to ensure all tests pass.
2. Use the ConventionalCommitParser with different configurations:
   • No allowed_scopes: Behavior remains unchanged.
   • allowed_scopes defined: Only commits with matching scopes should be allowed.
   • Commit with no scope: Should be rejected when allowed_scopes is defined.

PR Completion Checklist

• Reviewed & followed the Contributor Guidelines
• Changes Implemented & Validation pipeline succeeds
• Commits follow the Conventional Commits standard
  and are separated into the proper commit type and scope (recommended order: test, build, feat/fix, docs)
• Appropriate Unit tests added/updated
• Appropriate End-to-End tests added/updated
• Appropriate Documentation added/updated and syntax validated for sphinx build (see Contributor Guidelines)