Fix Cobertura tests on Windows

Author: dvdoug

src/Report/Cobertura.php

@@ -132,7 +132,7 @@ public function process(CodeCoverage $coverage, ?string $target = null, ?string
                 $classElement = $document->createElement('class');
 
                 $classElement->setAttribute('name', $className);
-                $classElement->setAttribute('filename', str_replace($report->pathAsString() . '/', '', $item->pathAsString()));
+                $classElement->setAttribute('filename', str_replace($report->pathAsString() . DIRECTORY_SEPARATOR, '', $item->pathAsString()));
                 $classElement->setAttribute('line-rate', (string) $lineRate);
                 $classElement->setAttribute('branch-rate', (string) $branchRate);
                 $classElement->setAttribute('complexity', (string) $class['ccn']);
@@ -206,7 +206,7 @@ public function process(CodeCoverage $coverage, ?string $target = null, ?string
 
             $classElement = $document->createElement('class');
             $classElement->setAttribute('name', basename($item->pathAsString()));
-            $classElement->setAttribute('filename', str_replace($report->pathAsString() . '/', '', $item->pathAsString()));
+            $classElement->setAttribute('filename', str_replace($report->pathAsString() . DIRECTORY_SEPARATOR, '', $item->pathAsString()));
 
             $methodsElement = $document->createElement('methods');