Update BouncyCastle.Cryptography to 2.6.1

---
updated-dependencies:
- dependency-name: BouncyCastle.Cryptography
  dependency-version: 2.6.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

src/iTextSharp.LGPLv2.Core/iTextSharp.LGPLv2.Core.csproj

@@ -82,7 +82,7 @@
 
     <ItemGroup>
         <PackageReference Include="SkiaSharp" Version="3.119.0"/>
-        <PackageReference Include="BouncyCastle.Cryptography" Version="2.6.0"/>
+        <PackageReference Include="BouncyCastle.Cryptography" Version="2.6.1"/>
         <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All"/>
     </ItemGroup>