SimplePie merge upstream (#7967)

* https://github.com/simplepie/simplepie/pull/936 (Normalize encoding uppercase)

lib/composer.json

@@ -14,7 +14,7 @@
         "marienfressinaud/lib_opml": "0.5.1",
         "phpgt/cssxpath": "v1.3.0",
         "phpmailer/phpmailer": "6.10.0",
-        "simplepie/simplepie": "dev-freshrss#bb2cea342635b1b54fc34a0f0a1001e55d15064a"
+        "simplepie/simplepie": "dev-freshrss#d381ca57e9c57e251a47de2b577846503c3030ce"
     },
     "config": {
         "sort-packages": true,

lib/simplepie/simplepie/src/XML/Declaration/Parser.php

@@ -242,7 +242,7 @@ class Parser
     public function encoding_value(): void
     {
         if ($encoding = $this->get_value()) {
-            $this->encoding = $encoding;
+            $this->encoding = strtoupper($encoding);
             $this->skip_whitespace();
             if ($this->has_data()) {
                 $this->state = self::STATE_STANDALONE_NAME;