Change license from Apache-2.0 to GPL-3.0-or-later (#72)

* Initial plan

* Change license from Apache-2.0 to GPL-3.0-or-later

Co-authored-by: dermatz <6103201+dermatz@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dermatz <6103201+dermatz@users.noreply.github.com>

Author: Copilot

CONTRIBUTING.md

@@ -23,8 +23,8 @@ We appreciate your interest in contributing to MageForge! Please follow the guid
 
 ## Licensing
 
-- **License Information**: Review the [LICENSE](./LICENSES) file for detailed licensing information.
-- **Contribution License**: By contributing, you agree that your work will be licensed under the MIT License.
+- **License Information**: Review the [LICENSE](./LICENSE) file for detailed licensing information.
+- **Contribution License**: By contributing, you agree that your work will be licensed under the GPL-3.0-or-later license.
 
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