Polymake.jl 0.6.2 released

Today Polymake.jl 0.6.2 has been released.

Diff since v0.6.1

Merged pull requests:

• Move to scratchspaces and support many more architectures (#373) (@benlorenz)
• fixed interface for sparsevectors (#374) (@alexej-jordan)
• Introduce Array<Array<Set>> (#375) (@lkastner)
• CI: ensure updating a PR cancels running CI jobs for it (#376) (@fingolfin)
• Test EHRHART_POLYNOMIAL (#377) (@lkastner)
• CI: remove a few extra test runs (#378) (@benlorenz)