removed the ue of apt-spy2

I cannot see, what good the testing the mirrors every single time does. So
I removed it. This saves more than a minute execution time with no apparent
down side.

Author: eringerli

actions_install.sh

@@ -3,13 +3,6 @@
 set -e
 
 pip3 install clint pyserial setuptools adafruit-nrfutil
-sudo gem install apt-spy2
-sudo apt-spy2 check
-sudo apt-spy2 fix --commit
-
-# after selecting a specific mirror, we need to run 'apt-get update'
-sudo apt-get -o Acquire::Retries=3 update
-
 sudo apt-get -o Acquire::Retries=3 install -y libllvm8 -V
 
 sudo apt install -fy cppcheck clang-format-8