Fix chr() deprecation in ASCII85 last-tuple decoding (#793)

Fix chr() deprecation in ASCII85 last-tuple decoding

PR #779 fixed the chr() deprecation warning in the main decoding loop
but missed the "last tuple" switch/case block (lines 233-248) which
handles incomplete groups at the end of the encoded data.

The same issue applies: bit-shifted values ($tuple >> 16, $tuple >> 8)
can exceed 255, triggering:
  chr(): Providing a value not in-between 0 and 255 is deprecated

Apply `& 0xFF` bitmask to extract individual bytes, consistent with
the fix in the main loop.

Added test to PHPUnit/Integration/ParserTest.php to load and read demo PDF

Demo PDF would trigger the deprecation warnings without the fixes of
this PR.

---------

Co-authored-by: Konrad Abicht <abicht@mcon-consulting.de>

Author: Ciki

samples/bugs/PullRequest793.pdf

@@ -209,7 +209,7 @@ protected function decodeFilterASCII85Decode(string $data): string
                     if (255 < $tuple >> 24) {
                         $chr24Part = \chr(($tuple >> 24) % 256);
                     } else {
-                        $chr24Part = \chr($tuple >> 24);
+                        $chr24Part = \chr(($tuple >> 24) & 0xFF);
                     }
 
                     if (255 < $tuple) {
@@ -232,15 +232,15 @@ protected function decodeFilterASCII85Decode(string $data): string
         // last tuple (if any)
         switch ($group_pos) {
             case 4:
-                $decoded .= \chr($tuple >> 24).\chr($tuple >> 16).\chr($tuple >> 8);
+                $decoded .= \chr(($tuple >> 24) & 0xFF).\chr(($tuple >> 16) & 0xFF).\chr(($tuple >> 8) & 0xFF);
                 break;
 
             case 3:
-                $decoded .= \chr($tuple >> 24).\chr($tuple >> 16);
+                $decoded .= \chr(($tuple >> 24) & 0xFF).\chr(($tuple >> 16) & 0xFF);
                 break;
 
             case 2:
-                $decoded .= \chr($tuple >> 24);
+                $decoded .= \chr(($tuple >> 24) & 0xFF);
                 break;
 
             case 1:

src/Smalot/PdfParser/RawData/FilterHelper.php

@@ -438,6 +438,18 @@ public function testIgnoreEncryption(): void
 
         // without the configuration option set, an exception would be thrown.
     }
+
+    /**
+     * Tests a fix for chr() which threw deprecations when running PHP 8.5
+     *
+     * @see https://github.com/smalot/pdfparser/pull/793
+     */
+    public function testPullRequest793ChrDeprecationFix(): void
+    {
+        $document = (new Parser())->parseFile($this->rootDir.'/samples/bugs/PullRequest793.pdf');
+
+        $this->assertEquals('ASCII85 last-tuple overflow test', $document->getText());
+    }
 }
 
 class ParserSub extends Parser