Fix potential memory leak due to not calling imagedestroy on GdImage objects

app/Services/InstanceService.php

@@ -120,6 +120,9 @@ class InstanceService
 				$pixels[] = $row;
 			}
 
+			// Free the allocated GdImage object from memory:
+			imagedestroy($image);
+
 			$components_x = 4;
 			$components_y = 4;
 			$blurhash = Blurhash::encode($pixels, $components_x, $components_y);

app/Util/Media/Blurhash.php

@@ -44,6 +44,9 @@ class Blurhash {
 			$pixels[] = $row;
 		}
 
+		// Free the allocated GdImage object from memory:
+		imagedestroy($image);
+
 		$components_x = 4;
 		$components_y = 4;
 		$blurhash = BlurhashEngine::encode($pixels, $components_x, $components_y);