dotnet format is failing on CI

[jamescrosswell]

The Format workflow in CI is currently breaking with:
System.Exception: source text did not have an identifiable encoding

Example here

Seemingly there is an issue with dotnet format and LF line endings (vs CRLF line endings). The command runs fine on Windows.

Probably the simplest workaround is to run this workflow on the windows-latest runner (instead of macos-15).

[jamescrosswell]

It looks like this will be fixed in the 9.0.202 SDK release, once this is available.

For the time being, I've disabled rollForward behaviour in our global.json (which effectively pins the version of dotnet-format to the version that shipped with version 9.0.103 of the .NET SDK). See commit 33cea55 (this was done so that we could finally merge that PR).

Once 9.0.202 is available we can bump this... we could potentially consider enabling rollForward again but that does make our CI builds less deterministic. I'm included to leave it disabled and only bump the SDK version intentionally.