fkYAML version 0.3.0

Summary

This release contains some breaking changes in the basic_node's mapping node type so that fkYAML supports non-string-scalar nodes, such as mappings or integer scalars, as mapping keys.
Furthermore, from this release on, GCC-7 and GCC-8 are in the list of supported compilers and used for testing on GitHub Actions.

What's Changed

💥 Breaking Changes

• #240 Support explicit block mappings & non-scalar nodes as mapping keys #245 (fktn-k)
• #240 Support non-string scalar nodes as mapping keys #244 (fktn-k)
• Feature/238 apply correct noexcept #241 (fktn-k)

⚡ Improvements

• #240 Support non-string-scalar node keys in basic_node ctor with std::initializer_list #247 (fktn-k)
• #240 implement node comparison #243 (fktn-k)

🐛 Bug Fixes

• Fixed missing callings of fclose() in the unit tests #246 (fktn-k)

🤖 CI

• Add GCC compiler versions tested in GA workflows #248 (fktn-k)

📝 Documentation

• Update copyright description #249 (fktn-k)

Full Changelog: v0.2.3...v0.3.0