add dotnet path

.github/scripts/mac-action-runner-readme.txt

@@ -23,4 +23,8 @@ JDK (we need a specific JDK):
     sudo rm -fr /Library/PreferencePanes/JavaControlPanel.prefpane
 
 C++:
- - brew install cmake
+ - brew install cmake
+
+C#:
+ - .github/scripts/install-dotnet-on-osx.sh
+    (you need to repeat this step for each user account)

.github/scripts/run-tests-dotnet.sh

@@ -2,6 +2,8 @@
 
 set -euo pipefail
 
+export PATH=$PATH:~/.dotnet
+
 # we need to build the runtime before test run, since we used "--no-dependencies"
 # when we call dotnet cli for restore and build, in order to speed up