remmina: Update to 1.4.20

Changelog:
1.4.20
    appindicator or ayatana-appindicator is now a requirement
    NX, XDMCP and ST have been removed
    Use -DWITH_FREERDP3=ON if you are using the FreeRDP master branch
    libsodium is needed to build Remmina.
    webkit2gtk3 is needed to build the WWW plugin.
    -DWITH_KF5WALLET=ON is a new config option needed for the KWallet plugin (and the required kf5wallet libraries to build it).
    News can be turned off with -DWITH_NEWS=OFF\
    gtk-vnc is needed for the VNC plugin for GNOME and KVM, -DWITH_GVNC=ON

List of changes:

    Mark appindicator as required !2290 @antenore
    Disabling XDMCP, NX, and ST !2291 @antenore
    Remove plugins/st,xdmcp,nx for submodule replacement !2292 @antenore
    SSH tunnel MFA !2293 @antenore
    Adding connection profiles menu into the toolbar !2295 @antenore
    Resolve "Preferences buttons not working since v1.4.19" !2296 @antenore
    Some X11 related functions cleanup

1.4.19
    Use -DWITH_FREERDP3=ON if you are using the FreeRDP master branch
    libsodium is needed to build Remmina.
    webkit2gtk3 is needed to build the WWW plugin.
    -DWITH_KF5WALLET=ON is a new config option needed for the KWallet plugin (and the required kf5wallet libraries to build it).
    News can be turned off with -DWITH_NEWS=OFF\
    gtk-vnc is needed for the VNC plugin for GNOME and KVM, -DWITH_GVNC=ON
    appindicator or ayatana-appindicator is now a requirement

List of changes:

    Fix Freerdp Git Revision !2277 (merged) @matty-r
    UI improvements and cleanup !2278 (merged) @antenore
    Desktop integration for the Remmina SNAP !2279 (merged) @antenore
    Add process-control to the remmina snap !2276 (merged) @antenore
    Adding SSH_AGENT support to the snap package !2280 (merged) @antenore
    Adding option to disable smooth scrolling !2281 (merged) @antenore
    Scrolled Viewport: use viewport_motion_handler as the only timeout indicator !2282 (merged) @cth451
    Adding TCP redirection through rdp2tcp !2283 (merged) @antenore
    Added setting for RDP number of reconnect attempts !2284 (merged) @antenore
    Add RDP reconnect interrupt on window close, fix crash introduced with 7c13b918. Should fix #2079 !2286 (merged) @giox069
    Removing GtkStatusIcon as deprecated !2285 (merged) @antenore
    Adding advanced option to share multiple folders !2287 (merged) @antenore
    Profile list grabs the focus when search is hidden !2288 (merged) @antenore

1.4.18
    Use -DWITH_FREERDP3=ON if you are using the FreeRDP master branch
    libsodium is needed to build Remmina.
    webkit2gtk3 is needed to build the WWW plugin.
    -DWITH_KF5WALLET=ON is a new config option needed for the KWallet plugin (and the required kf5wallet libraries to build it).
    News can be turned off with -DWITH_NEWS=OFF\
    gtk-vnc is needed for the VNC plugin for GNOME and KVM, -DWITH_GVNC=ON

List of changes:

    [SNAP] Removing unsupported architectures !2268 @antenore
    Try more shells as launcher if default isn't found !2269 @cirelli94
    Minor fixes for v1.4.17 !2270 @antenore
    SSH session improvements !2271 @antenore
    Fixes - Auto-start file created on tray icon disabled !2272 @antenore
    RDP: Remove older usage of ClientHostname @giox069
    Fix libfreerdp version check @giox069
    Explicitly set user resolution to a multiple of 4 !2273 @antenore
    Code refactoring - ASAN exceptions !2274 @antenore

(ryoon)