ci(tests): Add libevent for pytest

tmux: error while loading shared libraries: libevent-2.1.so.7: cannot open shared object file: No such file or directory

Author: tony

.github/workflows/tests.yml

@@ -70,6 +70,7 @@ jobs:
     - name: Test with pytest
       continue-on-error: ${{ matrix.tmux-version == 'master' }}
       run: |
+        sudo apt install libevent-2.1-7
         export PATH=$HOME/tmux-builds/tmux-${{ matrix.tmux-version }}/bin:$PATH
         ls $HOME/tmux-builds/tmux-${{ matrix.tmux-version }}/bin
         tmux -V