Add license change to CHANGELOG

[jreineckearm]

Fixes

• [Feature Request]: Include GDB builds for Arm in CMSIS Debugger extension #337

Changes

• Adds license change to CHANGELOG for transparency.

Screenshots

Checklist

• 🤖 This change is covered by unit tests (if applicable).
• 🤹 Manual testing has been performed (if necessary).
• 🛡️ Security impacts have been considered (if relevant).
• 📖 Documentation updates are complete (if required).
• 🧠 Third-party dependencies and TPIP updated (if required).

[jkrech]

LGTM

[jreineckearm]

Docs only, change. Build and test and CodeQL workflows won't run.