Bump version to 7.21.1

[habbes]

Updates version to 7.21.1. This release includes a dependency configuration change that fixes a regression #2954

[robertmclaws]

I just want to point out that if we modernized the solution configuration and build system here like I did with Restier, we wouldn't need to do these things... because Visual Studio would calculate the dependencies for the .nupkg file automatically.

[habbes]

I just want to point out that if we modernized the solution configuration and build system here like I did with Restier, we wouldn't need to do these things... because Visual Studio would calculate the dependencies for the .nupkg file automatically.

I think we should do these once we get over the ODL 8 release (or after we've completed the major ODL 8 work, unless modernizing the solution would be a quick fix), so the ODL 8 branch could move to modern build config, modern analyzers, etc. I think similar discussions have been raised. Let me see if I can locate the issues, otherwise we should create one to track this.