Merge pull request #3276 from boegel/disable_apt_spy2

stop using apt-spy2 to pick an alternative mirror, it's expensive and may result in picking a faulty mirror...

.github/workflows/unit_tests.yml

@@ -49,14 +49,9 @@ jobs:
 
     - name: install OS & Python packages
       run: |
-        # use apt-spy2 to select closest apt mirror,
-        # which helps avoid connectivity issues in Azure;
-        # see https://github.com/actions/virtual-environments/issues/675
-        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 update
+        # disable apt-get update, we don't really need it,
+        # and it does more harm than good (it's fairly expensive, and it results in flaky test runs)
+        # sudo apt-get update
         # for modules tool
         sudo apt-get install lua5.2 liblua5.2-dev lua-filesystem lua-posix tcl tcl-dev
         # fix for lua-posix packaging issue, see https://bugs.launchpad.net/ubuntu/+source/lua-posix/+bug/1752082