Second attempt at AppImage fix (#3304)

Author: ferdnyc

installer/launch-linux.sh

@@ -9,7 +9,7 @@ export QT_PLUGIN_PATH="."
 # For Debian-based systems with newer openssl, see:
 # https://github.com/OpenShot/openshot-qt/issues/3242
 # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=918727 
-export OPENSSL_CONF=/dev/null
+export OPENSSL_CONF="/dev/null"
 
 # Launch application
 HERE="$(dirname "$(readlink -f "${0}")")"