test: remove deprecated MT_RAND_PHP and fix mt_rand() upper bound

[vlakoff]

Fixes #176.

The test previously seeded error locations with:

do {
    $errorLocation = mt_rand(0, $blockSize);
} while (0 !== $errorLocations[$errorLocation]);

This allowed $errorLocation to equal $blockSize, which is out of range for an array of length $blockSize (valid indices are 0 … $blockSize - 1).

• With MT_RAND_PHP, the upper bound was not hit in practice.
• With MT_RAND_MT19937, the upper bound is reached, causing an OutOfBoundsException.

Fix: Correct the upper bound to $blockSize - 1:

do {
    $errorLocation = mt_rand(0, $blockSize - 1);
} while (0 !== $errorLocations[$errorLocation]);

[vlakoff]

By the way, this code is useless and looks like some sort of leftover:

BaconQrCode/test/Common/BitArrayTest.php

Lines 114 to 116 in bd2370d

	if ($actual !== $expected) {
	$array->getNextSet($query);
	}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.58%. Comparing base (bd2370d) to head (f64a4f4).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #208   +/-   ##
=========================================
  Coverage     70.58%   70.58%           
  Complexity      995      995           
=========================================
  Files            49       49           
  Lines          3182     3182           
=========================================
  Hits           2246     2246           
  Misses          936      936           

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[DASPRiD]

By the way, this code is useless and looks like some sort of leftover:

BaconQrCode/test/Common/BitArrayTest.php

Lines 114 to 116 in bd2370d

	if ($actual !== $expected) {
	$array->getNextSet($query);
	}

You are right, looking at the source test, that line does not exist and can be removed.

[DASPRiD]

LGTM, you can remove that useless test code in another PR :)