Bump AkkaVersion and AkkaHostingVersion to 1.5.20 (#264)

* Bump AkkaVersion and AkkaHostingVersion to 1.5.20

* Bump xunit and xunit.runner to 2.8.0

Author: Arkatufus

src/Directory.Packages.props

@@ -1,7 +1,7 @@
 <Project>
   <PropertyGroup>
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
-    <AkkaVersion>1.5.15</AkkaVersion>
+    <AkkaVersion>1.5.20</AkkaVersion>
     <AkkaHostingVersion>1.5.20</AkkaHostingVersion>
 
     <!-- Install from version 5.0.11 included all the way up to 8.x.x, but don't go up a major version -->
@@ -23,8 +23,8 @@
     <PackageVersion Include="Akka.Hosting.TestKit" Version="$(AkkaVersion)" />
     <PackageVersion Include="FluentAssertions" Version="6.12.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageVersion Include="xunit" Version="2.6.6" />
-    <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.7" />
+    <PackageVersion Include="xunit" Version="2.8.0" />
+    <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.0" />
     <PackageVersion Include="Akka.TestKit.Xunit2" Version="$(AkkaVersion)" />
     <PackageVersion Include="Akka.Persistence.Sql.TestKit" Version="$(AkkaVersion)" />
     <PackageVersion Include="Docker.DotNet" Version="3.125.15" />