CI is failing under Ubuntu / Debian - gpg key errors

[geerlingguy]

For example:

fatal: [instance]: FAILED! => {"changed": false, "cmd": "/usr/bin/apt-key --keyring /etc/apt/trusted.gpg.d/erlang-E495BB49CC4BBE5B.gpg add -", "msg": "Unable to add a key from binary data", "rc": 2, "stderr": "Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).\ngpg: error running '/usr/bin/gpg-agent': probably not installed\ngpg: failed to start agent '/usr/bin/gpg-agent': Configuration error\ngpg: can't connect to the agent: Configuration error\n", "stderr_lines": ["Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).", "gpg: error running '/usr/bin/gpg-agent': probably not installed", "gpg: failed to start agent '/usr/bin/gpg-agent': Configuration error", "gpg: can't connect to the agent: Configuration error"], "stdout": "", "stdout_lines": []}

We need to update the code after the PR #20 was merged—so we use the new method of adding keys.