Upgrade to PHP 8.1 (#6711)

* Upgrade to PHP 8.1
As discussed in https://github.com/FreshRSS/FreshRSS/discussions/5474

https://www.php.net/releases/8.0/en.php
https://www.php.net/releases/8.1/en.php

Upgrade to available native type declarations
https://php.net/language.types.declarations

Upgrade to https://phpunit.de/announcements/phpunit-10.html which requires PHP 8.1+ (good timing, as version 9 was not maintained anymore)

Upgrade `:oldest` Docker dev image to oldest Alpine version supporting PHP 8.1: Alpine 3.16, which includes PHP 8.1.22.

* Include 6736
https://github.com/FreshRSS/FreshRSS/pull/6736

1 files changed, 3 insertions, 3 deletions

diff --git a/app/Models/Search.php b/app/Models/Search.php
index 31b3d8d5a..7eaf741c3 100644
--- a/app/Models/Search.php
+++ b/app/Models/Search.php
@@ -135,11 +135,11 @@ class FreshRSS_Search {
 	}
 
 	/** @return array<int>|'*'|null */
-	public function getLabelIds() {
+	public function getLabelIds(): array|string|null {
 		return $this->label_ids;
 	}
 	/** @return array<int>|'*'|null */
-	public function getNotLabelIds() {
+	public function getNotLabelIds(): array|string|null {
 		return $this->not_label_ids;
 	}
 	/** @return array<string>|null */
@@ -242,7 +242,7 @@ class FreshRSS_Search {
 	 * @param array<string>|string $value
 	 * @return ($value is array ? array<string> : string)
 	 */
-	private static function decodeSpaces($value) {
+	private static function decodeSpaces($value): array|string {
 		if (is_array($value)) {
 			for ($i = count($value) - 1; $i >= 0; $i--) {
 				$value[$i] = self::decodeSpaces($value[$i]);