Symfony 5 support

[deileo]

I believe currently it is not possible to use this bundle with Symfony 5.
Will this bundle have support for it ?

[mcorteel-harel]

@schmittjoh Are there any plans for this? Is merging #246 an option?
My project needs this to finally upgrade to Symfony 5 and I could spend some time ironing out the remaining issues if you want.

As for Symfony 3 support, this could be a major version of the bundle. End of life was reached by Symfony 3.4 in November 2021 anyway.

[fnagel]

My branch works for Symfony 5.4 and should be ready for Symfony 6.4 (still working on it): https://github.com/fnagel/JMSJobQueueBundle