Changed http to https for api requests

app/src/main/java/com/sirekanyan/knigopis/Constants.kt

@@ -1,6 +1,6 @@
 package com.sirekanyan.knigopis
 
-const val MAIN_API = "http://api.knigopis.com"
+const val MAIN_API = "https://api.knigopis.com"
 const val STATIC_API = "https://knigopis.tk/img"
 const val DATE_FORMAT = "yyyy-MM-dd HH:mm:ss"
 const val MIN_BOOK_PRIORITY = 1