Bump System.Text.Encoding.CodePages from 9.0.9 to 9.0.16

---
updated-dependencies:
- dependency-name: System.Text.Encoding.CodePages
  dependency-version: 9.0.16
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: System.Text.Encoding.CodePages
  dependency-version: 9.0.16
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

MimeKit/MimeKit.csproj

@@ -74,7 +74,7 @@
   </ItemGroup>
 
   <ItemGroup Condition=" $(TargetFramework.StartsWith('netstandard2.')) ">
-    <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.9" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.16" />
   </ItemGroup>
 
   <ItemGroup Condition=" ! $(TargetFramework.StartsWith('net4')) ">

MimeKit/MimeKitLite.csproj

@@ -63,7 +63,7 @@
   </PropertyGroup>
 
   <ItemGroup Condition=" $(TargetFramework.StartsWith('netstandard2.')) ">
-    <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.9" />
+    <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.16" />
   </ItemGroup>
 
   <ItemGroup Condition=" $(TargetFramework.StartsWith('net4')) Or '$(TargetFramework)' == 'netstandard2.0' ">