openvpn: 2.4.4 -> 2.4.5

Semi-automatic update. These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 2.4.5 with grep in /nix/store/a2wdxd4c08b1gilnj2mcvkmvpnqxw942-openvpn-2.4.5
- found 2.4.5 in filename of file in /nix/store/a2wdxd4c08b1gilnj2mcvkmvpnqxw942-openvpn-2.4.5