Always publish image alt text

Previous code would discard the image alt-text if the user finished writing the text before the image had finished uploading.

This code ensures the text is set after the image has completed uploading.

app/src/main/java/com/keylesspalace/tusky/network/ProgressRequestBody.java

@@ -67,8 +67,10 @@ public final class ProgressRequestBody extends RequestBody {
                 uploaded += read;
                 sink.write(buffer, 0, read);
             }
+
+            uploadListener.onProgressUpdate((int)(100 * uploaded / contentLength));
         } finally {
             content.close();
         }
     }
-}
+}