fix: resolve PHP deprecation of imagedestroy

> Prior to PHP 8.0.0, imagedestroy() freed any memory associated with the image resource.
> As of 8.0.0, the GD extension uses objects instead of resources, and objects cannot be explicitly closed.

With PHP 8.5 this is deprecated and causes a deprecation warning!

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

apps/theming/lib/ImageManager.php

@@ -265,12 +265,7 @@ public function updateImage(string $key, string $tmpFile): string {
 						}
 					}
 					$tmpFile = $newTmpFile;
-					imagedestroy($outputImage);
 				} catch (\Exception $e) {
-					if (isset($outputImage) && is_resource($outputImage) || $outputImage instanceof \GdImage) {
-						imagedestroy($outputImage);
-					}
-
 					$this->logger->debug($e->getMessage());
 				}
 			}

lib/private/Image.php

@@ -508,7 +508,6 @@ public function fixOrientation(): bool {
 			if ($res) {
 				if (imagealphablending($res, true)) {
 					if (imagesavealpha($res, true)) {
-						imagedestroy($this->resource);
 						$this->resource = $res;
 						return true;
 					} else {
@@ -926,7 +925,6 @@ public function preciseResizeNew(int $width, int $height): \GdImage|false {
 		$res = imagecopyresampled($process, $this->resource, 0, 0, 0, 0, $width, $height, $widthOrig, $heightOrig);
 		if ($res === false) {
 			$this->logger->debug(__METHOD__ . '(): Error re-sampling process image', ['app' => 'core']);
-			imagedestroy($process);
 			return false;
 		}
 		return $process;
@@ -988,7 +986,6 @@ public function centerCrop(int $size = 0): bool {
 			$this->logger->debug('Image->centerCrop, Error re-sampling process image ' . $width . 'x' . $height, ['app' => 'core']);
 			return false;
 		}
-		imagedestroy($this->resource);
 		$this->resource = $process;
 		return true;
 	}
@@ -1009,7 +1006,6 @@ public function crop(int $x, int $y, int $w, int $h): bool {
 			return false;
 		}
 		$result = $this->cropNew($x, $y, $w, $h);
-		imagedestroy($this->resource);
 		$this->resource = $result;
 		return $this->valid();
 	}