github-runner: Avoid /homeless-shelter bug (#170892)

This commit fix "homeless-shelter" bug that you sometimes get on local
builds:

"Failed to read NuGet.Config due to unauthorized access. Path:
'/homeless-shelter/.config/NuGet/NuGet.Config"

Sets HOME envrioment varibale in derivation to /tmp.

pkgs/development/tools/continuous-integration/github-runner/default.nix

@@ -105,6 +105,8 @@ stdenv.mkDerivation rec {
   configurePhase = ''
     runHook preConfigure
 
+    export HOME=$(mktemp -d)
+
     # Never use nuget.org
     nuget sources Disable -Name "nuget.org"