Support monolog 2.0*

[virhi]

This PR opens the possibility to use the bundle with the last version of SF5 that required monolog 2.X

What I did:

• [x] Change the dependency configuration
• [x] Update CollectionHandler

[michaelKaefer]

This is needed for Symfony 5.1 support, please merge it if possible.

[florianfish]

@michaelKaefer do you have a solution to install it ? thanks.

[michaelKaefer]

@florianfish Yes, but it is private. I just forked it and applied the same changes as in this PR, then released a version of my fork, added the repo of my fork to composer repos and installed my fork.

[florianfish]

@michaelKaefer sorry i never did how do you do ? Thanks

[michaelKaefer]

@florianfish I already told you what I did, which part is unclear? Also feel free to contact me elsewhere to not spam the people here :)

[MueR]

Can this be merged please?

[dutsik]

Hey guys! Please merge it!