[Core] Use unztell64 in FileAccessZIP to ensure 64 bit return

(cherry picked from commit efccebd3db90d7baf0947cd02612ab987ab87868)

core/io/file_access_zip.cpp

@@ -278,7 +278,7 @@ void FileAccessZip::seek_end(int64_t p_position) {
 
 uint64_t FileAccessZip::get_position() const {
 	ERR_FAIL_COND_V(!zfile, 0);
-	return unztell(zfile);
+	return unztell64(zfile);
 }
 
 uint64_t FileAccessZip::get_len() const {