FEDX-1601: Fixed issue where changlogs can have inconsistent formats

[matthewnitschke-wk]

FEDX-1601

Dart changelogs do not have to have consistent version header nesting:

• https://github.com/Workiva/dependency_validator/blob/master/CHANGELOG.md?plain=1#L1
• https://github.com/Workiva/dart_dev/blob/master/CHANGELOG.md?plain=1#L3

Instead of strictly checking ##, this PR updates the validate-publish job to only check for # <version>, this will match any depth markdown header

[aviary3-wk]

Security Insights

No security relevant content was detected by automated scans.

Action Items

• Review PR for security impact; comment "security review required" if needed or unsure
• Verify aviary.yaml coverage of security relevant code

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[dustinlessard-wf]

QA+1
@Workiva/release-management-p

[rmconsole-wf]

+1 from RM