It it possible to opt-out of the check for target framework(s) by using the CakeContribGuidelinesOmitTargetFramework setting
and setting it's Include to the target framework that should not be checked.
(Keep in mind, though, that it is not recommended to opt-out of this feature)
<ItemGroup>
<CakeContribGuidelinesOmitTargetFramework Include="netstandard2.0" />
<CakeContribGuidelinesOmitTargetFramework Include="net461" />
</ItemGroup>