Floating Point and Php Nightly 8.4

Fix PHPOffice#3896. It appears that floating-point arithmetic will give different results in Php 8.4 vs. all earlier releases. This causes tests to fail in the nightly run for ROUNDDOWN, ROUNDUP, and AMORDEGRC. I imagine this won't be the last we hear of this. The failures are a distraction when reviewing PR's. This PR eliminates the distraction by adding in a fudge factor for Php 8.4+ while not changing Php 8.3-. It is not a particularly robust solution, but it should be stable for Php 8.3-, and good enough for Php 8.4+ while I study if a better solution is available.

Author: oleibman

src/PhpSpreadsheet/Calculation/Financial/Amortization.php

@@ -9,6 +9,8 @@
 
 class Amortization
 {
+    private const ROUNDING_ADJUSTMENT = (PHP_VERSION_ID < 80400) ? 0 : 1e-14;
+
     /**
      * AMORDEGRC.
      *
@@ -80,6 +82,7 @@ public static function AMORDEGRC(
         $amortiseCoeff = self::getAmortizationCoefficient($rate);
 
         $rate *= $amortiseCoeff;
+        $rate += self::ROUNDING_ADJUSTMENT;
         $fNRate = round($yearFrac * $rate * $cost, 0);
         $cost -= $fNRate;
         $fRest = $cost - $salvage;

src/PhpSpreadsheet/Calculation/MathTrig/Round.php

@@ -10,6 +10,8 @@ class Round
 {
     use ArrayEnabled;
 
+    private const ROUNDING_ADJUSTMENT = (PHP_VERSION_ID < 80400) ? 0 : 1e-14;
+
     /**
      * ROUND.
      *
@@ -68,10 +70,10 @@ public static function up($number, $digits): array|string|float
         }
 
         if ($number < 0.0) {
-            return round($number - 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_DOWN);
+            return round($number - 0.5 * 0.1 ** $digits + self::ROUNDING_ADJUSTMENT, $digits, PHP_ROUND_HALF_DOWN);
         }
 
-        return round($number + 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_DOWN);
+        return round($number + 0.5 * 0.1 ** $digits - self::ROUNDING_ADJUSTMENT, $digits, PHP_ROUND_HALF_DOWN);
     }
 
     /**
@@ -104,10 +106,10 @@ public static function down($number, $digits): array|string|float
         }
 
         if ($number < 0.0) {
-            return round($number + 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_UP);
+            return round($number + 0.5 * 0.1 ** $digits - self::ROUNDING_ADJUSTMENT, $digits, PHP_ROUND_HALF_UP);
         }
 
-        return round($number - 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_UP);
+        return round($number - 0.5 * 0.1 ** $digits + self::ROUNDING_ADJUSTMENT, $digits, PHP_ROUND_HALF_UP);
     }
 
     /**