getDownloadUrl.php does not handle version=8.5.7 correctly

[mkupper]

A recent update to Notepad++ brought the format of the internal version number in alignment with the published version number.

Notepad++ v8.5.6's internal version number is 8.56 - The internal version number does not have the dot between the 5 and 6.
Notepad++ v8.5.7's internal version number is 8.5.7 - The internal and public version numbers are now the same string.

This change to Notepad++ breaks code had been getting the internal version number from the notepad++.exe and passing it to https://notepad-plus-plus.org/update/getDownloadUrl.php to see if Notepad++ was up to date.

Please see https://community.notepad-plus-plus.org/topic/24926/needtobeupdated-is-always-yes/ both for background details and a suggested code fix to getDownloadUrl.php