[skolo] Install Python3 on NFS RPIs

This resolved to python 3.4

Bug: skia:11875
Change-Id: Ideccb3219d3ccfffabda321fda461c98f0dbb2b7
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/398939
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
diff --git a/skolo/raspberry-pi/setup-swarming.sh b/skolo/raspberry-pi/setup-swarming.sh
index d9c3add..c86f122 100644
--- a/skolo/raspberry-pi/setup-swarming.sh
+++ b/skolo/raspberry-pi/setup-swarming.sh
@@ -20,7 +20,8 @@
 
 # This took a very long time for me.  Maybe just a fluke
 apt-get update
-apt-get install libusb-1.0-0-dev libssl-dev openssl time build-essential swig python-m2crypto ntpdate python-pip git android-tools-adb collectd --no-install-recommends
+apt-get install libusb-1.0-0-dev libssl-dev openssl time build-essential swig python-m2crypto ntpdate python-pip \
+  git android-tools-adb collectd python3 --no-install-recommends
 # Disable dhcp, otherwise RPIs can get assigned TWO IP addresses.
 apt-get purge dhcpd5