Update dependencies from https://github.com/dotnet/winforms build 20200331.1 (#2830)

- Microsoft.Private.Winforms - 5.0.0-preview.3.20181.1

Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

Author: dotnet-maestro[bot]

eng/Version.Details.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
   <ProductDependencies>
-    <Dependency Name="Microsoft.Private.Winforms" Version="5.0.0-preview.3.20180.1">
+    <Dependency Name="Microsoft.Private.Winforms" Version="5.0.0-preview.3.20181.1">
       <Uri>https://github.com/dotnet/winforms</Uri>
-      <Sha>8138bd0e8bd045589aa735ee1501acec40923eb6</Sha>
+      <Sha>17d421f36541633c21682b297ca30740d8b539e1</Sha>
     </Dependency>
   </ProductDependencies>
   <ToolsetDependencies>
@@ -99,7 +99,7 @@
       Temporarily remove ApiCompat depenendency from this branch 
       to prevent DARC from updating this automatically. 
       This is being pinned to 5.0.0-beta.20162.3 for now.
-    --> 
+    -->
     <!--<Dependency Name="Microsoft.DotNet.ApiCompat" Version="5.0.0-beta.20162.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
       <Sha>16d4350184cf362cd59807b589d1c93803025abc</Sha>

eng/Versions.props

@@ -9,7 +9,7 @@
   </PropertyGroup>
   <!-- NuGet Package Versions -->
   <PropertyGroup>
-    <MicrosoftPrivateWinformsVersion>5.0.0-preview.3.20180.1</MicrosoftPrivateWinformsVersion>
+    <MicrosoftPrivateWinformsVersion>5.0.0-preview.3.20181.1</MicrosoftPrivateWinformsVersion>
   </PropertyGroup>
   <!-- Packages that come from https://github.com/dotnet/coreclr -->
   <PropertyGroup>