coin: Write provisioning environment variables to ~/.zshrc as well

The default shell on macOS 10.15+ changed to zsh, so we need to ensure
the environment variables are picked up by that as well.

Change-Id: Ib8c8d8017c0d22fdbbf429936876824d386d4f4c
Reviewed-by: Heikki Halmet <heikki.halmet@qt.io>

coin/provisioning/common/unix/SetEnvVar.sh

@@ -47,5 +47,6 @@ function SetEnvVar {
         echo "export $name=$path" >> ~/.profile
     else
         echo "export $name=$path" >> ~/.bashrc
+        echo "export $name=$path" >> ~/.zshrc
     fi
 }