[ci skip] Remove RC1 from 8.1.7 in the NEWS file

Author: ramsey

NEWS

@@ -6,7 +6,7 @@ PHP                                                                        NEWS
   . mb_detect_encoding recognizes all letters in Czech alphabet (alexdowad)
   . mb_detect_encoding recognizes all letters in Hungarian alphabet (alexdowad)
 
-26 May 2022, PHP 8.1.7RC1
+26 May 2022, PHP 8.1.7
 
 - CLI:
   . Fixed bug GH-8575 (CLI closes standard streams too early). (Levi Morrison)