Update version.props to 8.1.2 and propose release notes (#2889)

* Update version.props

* Update CHANGELOG.md

CHANGELOG.md

@@ -1,5 +1,14 @@
 See the [releases](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/releases) for details on bug fixes and added features.
 
+8.1.2
+=====
+### Bug fixes
+- CaseSensitiveClaimsIdentity.Clone() now returns a `CaseSensitiveClaimsIdentity` as expected. See [2879](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/pull/2879)
+- Multiple unused and unusable (for the moment) public APIs were removed. These were introduced by mistake leaking from the work done on logging and exception handling. See [2888](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/pull/2888). No major version changed needed as these APIs were not usable per se.
+
+### Fundamentals
+- Enabled PublicApiAnalyzers to better understand and trace changes to the public API. See[2782](https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/pull/2782)
+
 8.1.1
 =====
 ### Bug fixes

build/version.props

@@ -2,7 +2,7 @@
 <Project>
 <!-- MicrosoftIdentityModelVersion  -->
   <PropertyGroup>
-    <MicrosoftIdentityModelCurrentVersion>8.1.1</MicrosoftIdentityModelCurrentVersion>
+    <MicrosoftIdentityModelCurrentVersion>8.1.2</MicrosoftIdentityModelCurrentVersion>
 
     <PreviewVersionSuffix Condition="'$(PreviewVersionSuffix)' == '' and '$(BuildingInsideVisualStudio)' != 'true'">preview-$([System.DateTime]::Now.AddYears(-2019).Year)$([System.DateTime]::Now.ToString("MMddHHmmss"))</PreviewVersionSuffix>
     <!--VS re-evaluates the variables, so having seconds or minutes creates an infinite loop of package updates-->