Update Async generator to 0.8.2.12

This fix the generation bug which previously had to be reverted after
each generation, see maca88/AsyncGenerator#133.

Author: fredericDelaporte

Tools/packages.config

@@ -7,7 +7,7 @@
   <package id="NUnit.Extension.NUnitV2ResultWriter" version="3.6.0" targetFramework="net461" />
   <package id="NUnit.Extension.TeamCityEventListener" version="1.0.2" targetFramework="net461" />
   <package id="NUnit.Extension.VSProjectLoader" version="3.6.0" targetFramework="net461" />
-  <package id="CSharpAsyncGenerator.CommandLine" version="0.8.2.11" targetFramework="net461" />
+  <package id="CSharpAsyncGenerator.CommandLine" version="0.8.2.12" targetFramework="net461" />
   <package id="vswhere" version="2.1.4" targetFramework="net461" />
   <package id="gitreleasemanager" version="0.7.0" targetFramework="net461" />
 </packages>