Update build.sh (#3449)

Fixed typo: "Build successful done!" -> "Build successfully done!"

Telegram Desktop Developer Certificate of Origin

By making a contribution to this project, I certify that:

(a) The contribution was created in whole by me or is based upon
    previous work that, to the best of my knowledge, is in the
    public domain and I have the right to put it in the public domain.

(d) I understand and agree that this project and the contribution are
    public and that a record of the contribution (including all
    metadata and personal information I submit with it, including my
    sign-off) is maintained indefinitely and may be redistributed.

(e) I am granting this work into the public domain.

Signed-off-by: Fake Id 30 <junayeed@protonmail.com>
(github: fakeid30)

.travis/build.sh

@@ -636,7 +636,7 @@ buildTelegram() {
 check() {
   local filePath="$UPSTREAM/out/Debug/Telegram"
   if test -f "$filePath"; then
-    success_msg "Build successful done! :)"
+    success_msg "Build successfully done! :)"
 
     local size;
     size=$(stat -c %s "$filePath")