[CLEANUP] Rector: Change return type based on strict returns type operations (#587)

This applies the rule BoolReturnTypeFromStrictScalarReturnsRector. For
Details see:
https://github.com/rectorphp/rector/blob/main/docs/rector_rules_overview.md#boolreturntypefromstrictscalarreturnsrector

Signed-off-by: Daniel Ziegenberg <[email protected]>

Author: ziegenberg

src/Parsing/ParserState.php

@@ -361,10 +361,7 @@ public function consumeComment()
         return $mComment;
     }
 
-    /**
-     * @return bool
-     */
-    public function isEnd()
+    public function isEnd(): bool
     {
         return $this->iCurrentPosition >= $this->iLength;
     }