Description:
------------
when using an opslimit (which equals the time_cost parameter in password_hash with argon2i) of 1 a warning is thrown.

this is a result of
https://github.com/php/php-src/blob/master/ext/sodium/libsodium.c#L1905-L1908

and the fact that the constant SODIUM_CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE is 2.

considering the process on how the argon2 RFC goes for parameter choice, a time factor of 1 is certainly not impossible, in fact especially if the server has a lot of RAM, chances are that one would choose a time of 1 and go for the ram instead of lowering the RAM and choosing a 2 or higher for time if the situation allows.

also as a side note the RFC even states that for argon2id (which is what sodium uses) that 1 pass maximizes the attack costs for the constant time of the defender.

https://tools.ietf.org/html/draft-irtf-cfrg-argon2-03#section-9.3

Test script:
---------------
<?php
header("Content-Type: text/plain");
if(defined("SODIUM_CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE")) {
    echo "NaCl Found. ".PHP_EOL;
    echo sodium_crypto_pwhash_str("test",1,1<<26).PHP_EOL;
}
else echo "no NaCl with pwhash".PHP_EOL;
?>

Expected result:
----------------
NaCl Found. 
$argon2id$v=19$m=65536,t=1,p=1$h1v/Fexw43PMyi6W8NRRGA$QiqKXRL+csDoLqLT7p282LxPM3kfwc4UlGE5BUBD45w

Actual result:
--------------
NaCl Found. 
<br />
<b>Warning</b>:  number of operations for the password hashing function is low in <b>C:\xampp\htdocs\a2.php</b> on line <b>5</b><br />
$argon2id$v=19$m=65536,t=1,p=1$h1v/Fexw43PMyi6W8NRRGA$QiqKXRL+csDoLqLT7p282LxPM3kfwc4UlGE5BUBD45w