Use str_increment to avoid PHP 8.5 deprecation

Fixes #398.

Author: trowski

psalm.xml

@@ -17,13 +17,6 @@
     </projectFiles>
 
     <issueHandlers>
-        <StringIncrement>
-            <errorLevel type="suppress">
-                <directory name="examples"/>
-                <directory name="src"/>
-            </errorLevel>
-        </StringIncrement>
-
         <DocblockTypeContradiction>
             <errorLevel type="suppress">
                 <directory name="src"/>

src/Connection/Internal/Http2ConnectionProcessor.php

@@ -1426,7 +1426,11 @@ private function ping(): Future
         $this->pongDeferred = $deferred = new DeferredFuture;
         $this->pongWatcher = EventLoop::delay(self::PONG_TIMEOUT, fn () => $this->cancelPongWatcher(false));
 
-        $this->writeFrame(Http2Parser::PING, data: $this->counter++)->ignore();
+        $data = \PHP_VERSION_ID >= 80300
+            ? $this->counter = \str_increment($this->counter)
+            : $this->counter++;
+
+        $this->writeFrame(Http2Parser::PING, data: $data)->ignore();
 
         return $deferred->getFuture();
     }