Update APT repo key installation process

Author: jodal

.github/workflows/ci.yml

@@ -56,7 +56,8 @@ jobs:
           python-version: ${{ matrix.python }}
       - name: Install libspotify
         run: |
-          wget -q -O - https://apt.mopidy.com/mopidy.gpg | sudo apt-key add -
+          sudo mkdir -p /usr/local/share/keyrings
+          sudo wget -q -O /usr/local/share/keyrings/mopidy-archive-keyring.gpg https://apt.mopidy.com/mopidy.gpg
           sudo wget -q -O /etc/apt/sources.list.d/mopidy.list https://apt.mopidy.com/buster.list
           sudo apt-get update
           sudo apt-get install -y libspotify-dev