Bump BouncyCastle.Cryptography from 2.3.0 to 2.3.1 in /source (#129)

Bumps [BouncyCastle.Cryptography](https://github.com/bcgit/bc-csharp) from 2.3.0 to 2.3.1.
- [Commits](bcgit/bc-csharp@release-2.3.0...release-2.3.1)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

source/TuviProtonPrimitiveLib/TuviProtonPrimitiveLib.csproj

@@ -17,7 +17,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BouncyCastle.Cryptography" Version="2.3.0" />
+    <PackageReference Include="BouncyCastle.Cryptography" Version="2.3.1" />
   </ItemGroup>
 
   <ItemGroup>