Fix detection of copyright statements without year in copyright declarations

[dikshaa2909]

Fixes #4722

Description

This PR fixes detection of copyright statements that do not include a year in the declaration.

Previously, ScanCode required a year to be present alongside the copyright keyword. As a result, valid copyright statements such as:

• Copyright The OpenTelemetry Authors
• (c) The OpenTelemetry Authors

were not detected.

This update adjusts the copyright detection grammar to allow copyright declarations without a year component, while preserving existing behavior for statements that include years.

After this change, such statements are correctly identified and extracted.

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How to Reproduce (Before Fix)

Example file:

// Copyright The OpenTelemetry Authors

Run:

./scancode --json-pp result.json -c version.go

Previously returned:

"copyrights": []

---

After This Fix

The same scan now correctly detects:

{
  "copyright": "Copyright The OpenTelemetry Authors"
}

---

Notes

• Only the copyright detection logic was updated.
• No unrelated files were modified.
• Existing detection behavior for copyright statements with years remains unchanged.

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Checklist

• Reviewed contribution guidelines
• PR is descriptively titled and links the original issue
• Tests pass
• Commits are in a uniquely named feature branch and have no merge conflicts
• Documentation update not required
• CHANGELOG update not required unless requested