upstream Pico.php to php 8.1 compatibility

Signed-off-by: derMart <derMart@users.noreply.github.com>

Author: derMart

lib/Pico.php

@@ -104,7 +104,7 @@ public function __construct($rootDir, $configDir, $pluginsDir, $themesDir, $enab
 	 * @throws NotFoundException
 	 * @throws NotPermittedException
 	 */
-	public function run()
+	public function run() : string
 	{
 		return parent::run();
 	}
@@ -141,7 +141,7 @@ public function setRequestUrl($requestUrl)
 	 *
 	 * @return void
 	 */
-	protected function evaluateRequestUrl()
+	protected function evaluateRequestUrl() : void
 	{
 		// do nothing
 	}
@@ -157,7 +157,7 @@ protected function evaluateRequestUrl()
 	 * @throws NotFoundException
 	 * @throws NotPermittedException
 	 */
-	public function loadFileContent($absolutePath)
+	public function loadFileContent($absolutePath) : string
 	{
 		/** @var FolderInterface $folder */
 		/** @var string $basePath */
@@ -177,7 +177,7 @@ public function loadFileContent($absolutePath)
 	 * @return array
 	 * @throws ParseException
 	 */
-	public function parseFileMeta($rawContent, array $headers)
+	public function parseFileMeta($rawContent, array $headers) : array
 	{
 		$meta = parent::parseFileMeta($rawContent, $headers);
 		return $this->purifyFileMeta($meta);
@@ -212,7 +212,7 @@ protected function purifyFileMeta(array $meta): array
 	 *
 	 * @return string
 	 */
-	public function parseFileContent($markdown, $singleLine = false)
+	public function parseFileContent($markdown, $singleLine = false) : string
 	{
 		$content = parent::parseFileContent($markdown, $singleLine);
 		return $this->purifyFileContent($content);
@@ -275,7 +275,7 @@ private function getHtmlPurifierConfig(): HTMLPurifier_Config
 	 * @throws WebsiteInvalidFilesystemException
 	 * @throws InvalidPathException
 	 */
-	public function getFiles($absolutePath, $fileExtension = '', $order = \Pico::SORT_ASC)
+	public function getFiles($absolutePath, $fileExtension = '', $order = \Pico::SORT_ASC) : array
 	{
 		/** @var FolderInterface $folder */
 		/** @var string $basePath */
@@ -327,7 +327,7 @@ public function getFiles($absolutePath, $fileExtension = '', $order = \Pico::SOR
 	 * @throws WebsiteInvalidFilesystemException
 	 * @throws InvalidPathException
 	 */
-	public function getFilesGlob($absolutePathPattern, $order = \Pico::SORT_ASC)
+	public function getFilesGlob($absolutePathPattern, $order = \Pico::SORT_ASC) : array
 	{
 		/** @var FolderInterface $folder */
 		/** @var string $basePath */