fixes + phpstan

See fix at rector: rectorphp/rector-src#6164

Author: sreichel

app/code/core/Mage/Core/Model/Date.php

@@ -250,7 +250,7 @@ public function parseDateTime($dateTimeString, $dateTimeFormat)
             'm/d/y' => ['/^([0-9]{1,2})\/([0-9]{1,2})\/([0-9]{1,2})/', ['y' => 3, 'm' => 1, 'd' => 2]],
         ];
 
-        foreach (array_keys($formats) as $supportedFormat) {
+        foreach ($formats as $supportedFormat => $regRule) {
             if (strpos($dateTimeFormat, $supportedFormat, 0) !== false) {
                 $isSupportedFormatFound = true;
                 break;

app/code/core/Mage/Dataflow/Model/Batch.php

@@ -97,7 +97,7 @@ public function parseFieldList($row)
                 $this->_fieldList[$fieldName] = $fieldName;
             }
         }
-        unset($fieldName, $value, $row);
+        unset($fieldName, $row);
     }
 
     /**

phpstan.dist.baseline.neon

@@ -3400,11 +3400,6 @@ parameters:
 			count: 1
 			path: app/code/core/Mage/ImportExport/Model/Export/Entity/Product.php
 
-		-
-			message: "#^Offset int\\|string on non\\-empty\\-array\\<int\\|string, non\\-empty\\-array\\> in isset\\(\\) always exists and is not nullable\\.$#"
-			count: 2
-			path: app/code/core/Mage/ImportExport/Model/Export/Entity/Product.php
-
 		-
 			message: "#^Variable \\$collection might not be defined\\.$#"
 			count: 1