Merge pull request #220 from akkadotnet/dependabot/nuget/AkkaVersion-1.4.20

Bump AkkaVersion from 1.4.19 to 1.4.20

src/common.props

@@ -18,7 +18,7 @@
     <NoWarn>$(NoWarn);CS1591</NoWarn>
   </PropertyGroup>
   <PropertyGroup>
-    <AkkaVersion>1.4.19</AkkaVersion>
+    <AkkaVersion>1.4.20</AkkaVersion>
 
     <FluentAssertionsVersion>5.10.3</FluentAssertionsVersion>
     <XunitVersion>2.4.1</XunitVersion>