updated CHANGELOG for 2.4.0-BETA1
updated VERSION for 2.4.0-BETA1
[Security\Csrf] Split CsrfTokenGenerator into CsrfTokenManager and TokenGenerator
bug #9216 [Security\Csrf] Split CsrfTokenGenerator into CsrfTokenManager and TokenGenerator (bschussek)

This PR was merged into the master branch.

Discussion
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[Security\Csrf] Split CsrfTokenGenerator into CsrfTokenManager and TokenGenerator

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9210
| License       | MIT
| Doc PR        | -

This is a follow-up PR of #6554 that splits the CsrfTokenGenerator into two separate classes for generating and managing CSRF tokens. As a consequence, it is now possible to explicitly remove or refresh CSRF tokens if they should be used only once. See #9210 for more information.

Commits
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d4bb5f4 [Security\Csrf] Split CsrfTokenGenerator into CsrfTokenManager and TokenGenerator