ensure changelog uses softwraps

[ashleygwilliams]

chatted briefly with @zanieb and it seemes the github release notes use a different renderer than the code renderer (is this new???) and so their changelog was displayed with hard wraps. since we are processing that string anyways, we could/should update it to make sure it will display properly in github.

[zanieb]

Thanks! It's not pretty, but the problematic lines are at https://github.com/astral-sh/uv/blob/c3c05c46028de8903fbfea1235cc27804d9795ad/CHANGELOG.md?plain=1#L5-L29 which renders as

[zanieb]

Guess this is a duplicate of #218