Ignore SpringMethodVisibility check

Ignore the new `SpringMethodVisibility` on released versions since
the required changes can introduce subtle bugs.

See gh-17359

Author: philwebb

spring-boot-parent/src/checkstyle/checkstyle-suppressions.xml

@@ -4,6 +4,7 @@
 	"https://checkstyle.org/dtds/suppressions_1_2.dtd">
 <suppressions>
 	<suppress files="[\\/]target[\\/]" checks=".*" />
+	<suppress files=".*" checks="SpringMethodVisibility"/>
 	<suppress files="SpringApplicationTests\.java" checks="FinalClass" />
 	<suppress files=".+Configuration\.java" checks="HideUtilityClassConstructor" />
 	<suppress files=".+Application\.java" checks="HideUtilityClassConstructor" />