Adjust to use [[deprecated]] attribute

Issue/feature addressed

Removed Deprecated.hpp and replace with [[deprecated]] attribute

Proposed solution

n/a

Implementation

n/a

Tests

n/a

Suggested reviewers

Please suggest any people who would be appropriate to review your code.

Notes

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Checklist

• Functions and classes, or changes to them, are documented.
• [ ] User guide/documentation is updated.
• Changelog is updated.
• Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• [ ] License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).