Add better apt sources #80
Description
Description
The default runners in Github actions use pretty bad apt sources, causing unnecessary CI failures.
For example this pull request, which updates just a readme causes build failures because azure's Ubuntu mirror is flaky: https://github.com/ros-tooling/action-ros-ci/pull/129/checks?check_run_id=553125397.
I work around this in ros2/rmw_cyclonedds#134 but this repo is probably a better place to solve the problem so all downstream CI workflows don't have the same reliability problems.
2020-04-01T20:20:23.8861478Z ##[group]Invoking "sudo apt-get update"
2020-04-01T20:20:23.8867344Z [command]sudo apt-get update
...
2020-04-01T20:20:54.7635136Z Err:39 http://azure.archive.ubuntu.com/ubuntu bionic InRelease
2020-04-01T20:20:54.7635929Z Could not connect to azure.archive.ubuntu.com:80 (52.177.174.250), connection timed out
...
2020-04-01T20:22:12.2857474Z [command]sudo DEBIAN_FRONTEND=noninteractive RTI_NC_LICENSE_ACCEPTED=yes apt-get install --no-install-recommends --quiet --yes libssl-dev python3-dev build-essential clang cmake git lcov libc++-dev libc++abi-dev python3-catkin-pkg-modules python3-pip python3-vcstool wget libasio-dev libtinyxml2-dev libopensplice69 rti-connext-dds-5.3.1 python-rosdep
...
2020-04-01T20:22:43.1336618Z E: Failed to fetch http://azure.archive.ubuntu.com/ubuntu/pool/main/s/sgml-base/sgml-base_1.29_all.deb Could not connect to azure.archive.ubuntu.com:80 (52.177.174.250), connection timed out