NonceRepository creates keys containing reserved characters

[tomcdonnell]

Cache keys generated in https://github.com/oat-sa/lib-lti1p3-core/blob/master/src/Security/Nonce/NonceRepository.php do not conform to the requirements for cache keys according to PSR-6 and PSR-16. Specifically, the cache keys generated by this file can contain reserved characters {}()/@:.

https://www.php-fig.org/psr/psr-6/#definitions
https://www.php-fig.org/psr/psr-16/#12-definitions

Both documents linked to above state:

The following characters are reserved for future extensions and MUST NOT be supported by implementing libraries: {}()/@:

---

I ran into this problem while using this library together with php-cache. Cache keys generated by the NonceRepository caused an error in https://github.com/php-cache/cache/blob/master/src/Adapter/Common/AbstractCachePool.php. An exception was thrown in the validateKey() function.