Similar to https://github.com/spring-projects/spring-security/issues/13416

  • Update SecurityNamespaceHandler to require 6.3
  • Add spring-security-6.3.rnc and spring-security-6.3.xsd
  • Update spring.schemas; add lines for spring-security-6.3.xsd and change the setting for spring-security.xsd to point to spring-security-6.3.xsd
  • Point spring-security.xsd symlink to spring-security-6.3.xsd
  • Update XsdDocumentedTests to point to 6.3
  • Increment schema count in XsdDocumentedTests
  • Update SpringSecurityCoreVersion to 630L
  • Update RNC link in docs/modules/ROOT/pages/servlet/appendix/namespace/index.adoc
  • Change config/src/testresources/org/springframework/security/config/method-security.xml to reference the 6.3 schema
  • Update What's New to an empty 6.3 section
  • Update prepare-forward-merge to point to 6.3.x
  • Update gradle.properties version to 6.3.0-SNAPSHOT
  • Update security.tld tlib-version to 6.3
  • Update Dependabot configuration
  • Update release-scheduler.yml
  • Update samplesBranch in gradle.properties