Upgrade .NET runtime to 6.0 for tests, CodeGen and Benchmark#1136

Brunni wants to merge 2 commits intoangularsen:masterangularsen/UnitsNet:masterfrom

Brunni:upgrade_to_net60_tests_and_codegenBrunni/UnitsNet:upgrade_to_net60_tests_and_codegenCopy head branch name to clipboard