Fix typo in encoding charset making build fail

[NathanBnm]

There was a typo in the encoding charset of the extra French translation. This should fix build failing as discussed in #22.

[NathanBnm]

@RonnyDo you still have some build errors I don't really know what's causing them could you check?
Here is the compilation log:

$ ninja
[3/10] Compiling Vala source ../src/Wammer.vala ../src...../src/Utils/Utils.vala ../src/Services/Settings.vala.
FAILED: com.github.ronnydo.wammer@exe/src/Wammer.c com.github.ronnydo.wammer@exe/src/MainWindow.c com.github.ronnydo.wammer@exe/src/Services/Jammer.c com.github.ronnydo.wammer@exe/src/Services/JammerState.c com.github.ronnydo.wammer@exe/src/Utils/Utils.c com.github.ronnydo.wammer@exe/src/Services/Settings.c 
valac -C --debug --debug --pkg gtk+-3.0 --pkg granite --pkg gobject-2.0 --pkg glib-2.0 --color=always --directory com.github.ronnydo.wammer@exe --basedir ../ ../src/Wammer.vala ../src/MainWindow.vala ../src/Services/Jammer.vala ../src/Services/JammerState.vala ../src/Utils/Utils.vala ../src/Services/Settings.vala
../src/Utils/Utils.vala:24.9-24.14: error: syntax error, expected declaration
        public static List<string> get_Wi-Fi_interfaces () {
        ^^^^^^
../src/Utils/Utils.vala:24.16-24.21: error: syntax error, expected declaration
        public static List<string> get_Wi-Fi_interfaces () {
               ^^^^^^
../src/Utils/Utils.vala:25.51-25.51: error: syntax error, `new' modifier not allowed on creation method
            List<string> interface_list = new List<string> ();
                                                  ^
../src/Utils/Utils.vala:29.66-29.66: error: syntax error, `new' modifier not allowed on creation method
            SubprocessLauncher launcher = new SubprocessLauncher (SubprocessFlags.STDOUT_PIPE);    
                                                                 ^
../src/Utils/Utils.vala:41.63-41.63: error: syntax error, `new' modifier not allowed on creation method
                    DataInputStream dis = new DataInputStream (input_stream);
                                                              ^
../src/Utils/Utils.vala:63.9-63.14: error: syntax error, expected declaration
        public static string extract_Wi-Fi_interface (string input) {
        ^^^^^^
../src/Utils/Utils.vala:63.16-63.21: error: syntax error, expected declaration
        public static string extract_Wi-Fi_interface (string input) {
               ^^^^^^
../src/Utils/Utils.vala:67.41-67.41: error: syntax error, `new' modifier not allowed on creation method
                Regex regex = new Regex ("[a-zA-Z0-9]+");
                                        ^
Compilation failed: 8 error(s), 0 warning(s)
ninja: build stopped: subcommand failed.