Polymake.jl 0.5.6 released

Today Polymake.jl 0.5.6 has been released.

Diff since v0.5.5

Closed issues:

• finalize data.main_polymake_session atexit (#340)
• Make a release of Polymake.jl (resp. its helper packages) compatible with FLINT_jll v200.700.100 resp LoadFlint 0.5.1 (#345)
• Define a polytope as the intersection of halfspaces (#346)
• using Polymake crashes (#347)

Merged pull requests:

• Fix html for summary in Firefox (#339) (@saschatimme)
• CI: test on macos11 / update julia versions (#342) (@benlorenz)
• OscarCI: run oscar tests on master and release (#343) (@benlorenz)
• OscarCI: update workflow, use global axis to reduce combinations (#344) (@benlorenz)
• add polymake citation (#348) (@kalmarek)
• bump dependencies for polymake 4.4 (#349) (@benlorenz)