v7.0.0

DifferentialEquations v7.0.0

Diff since v6.21.0

Closed issues:

• Failed to precompile on M1 Mac (#830)
• Both Symbolics and Graphs export "degree"; uses of it in module ModelingToolkit must be qualified (#834)

Merged pull requests:

• Remove some background packages to greatly improve startup time (#835) (@ChrisRackauckas)
• Describe breaking changes in NEWS.md for v7 (#836) (@ChrisRackauckas)