Bump Microsoft.Build and Microsoft.NETFramework.ReferenceAssemblies

Bumps [Microsoft.Build](https://github.com/dotnet/msbuild) and [Microsoft.NETFramework.ReferenceAssemblies](https://github.com/Microsoft/dotnet). These dependencies needed to be updated together.

Updates `Microsoft.Build` from 17.10.4 to 17.12.6
- [Release notes](https://github.com/dotnet/msbuild/releases)
- [Changelog](https://github.com/dotnet/msbuild/blob/main/documentation/Changelog.md)
- [Commits](dotnet/msbuild@v17.10.4...v17.12.6)

Updates `Microsoft.NETFramework.ReferenceAssemblies` from 1.0.3 to 1.0.3
- [Commits](https://github.com/Microsoft/dotnet/commits)

---
updated-dependencies:
- dependency-name: Microsoft.Build
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: Microsoft.NETFramework.ReferenceAssemblies
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/NuGetizer.Tests/NuGetizer.Tests.csproj

@@ -12,7 +12,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
-    <PackageReference Include="Microsoft.Build" Version="17.10.4" ExcludeAssets="runtime" />
+    <PackageReference Include="Microsoft.Build" Version="17.12.6" ExcludeAssets="runtime" />
     <PackageReference Include="Microsoft.Build.Tasks.Core" Version="17.10.4" ExcludeAssets="runtime" />
     <PackageReference Include="Microsoft.Build.Locator" Version="1.7.8" />
     <PackageReference Include="MSBuild.StructuredLogger" Version="2.2.386" />