Remove compatibility with podio versions before v1.0

[tmadlener]

BEGINRELEASENOTES

• Remove compatibility with podio versions before 1.0

ENDRELEASENOTES

Since we already bumped this in our CMake config (#327), we can also remove this from our code.

Fixes #306

[jmcarcell]

These come from https://github.com/key4hep/key4hep-dev-utils/blob/main/defaults/.gitignore#L238, I think copied and pasted from the .gitignore in podio. The up to date ones seem to be so they could be in the central one even though it's not used for podio.

/python/podio/__version__.py
/python/podio_version.py

[tmadlener]

Ah, this is the global .gitignore, right? Why are we having podio specific ignores there? These should not appear in any repository, and the podio .gitignore is not globally managed.

[jmcarcell]

Ok they should be removed now, the changes here can be kept or not, they will be overwritten at some point anyway

[jmcarcell]

I opened other PRs with the same changes in other repositories:

• Delete the version checks for Podio before 1.0 k4FWCore#206
• Delete the version checks for Podio before 1.0 k4SimDelphes#120
• Delete the version checks for Podio before 1.0 k4EDM4hep2LcioConv#80

I think it's fine to merge them but they can also wait. The only case when keeping this code is useful is when someone wants to build the current versions on top of older versions of EDM4hep and Podio but not so old they don't work.