chore: migrate to nx 20.4.6

[Hotell]

some highlights

• feat(release): allow automated git push from version or changelog step nrwl/nx#29280 / needed for feat: migrate releases to Nx version plans and new decoupled release flow #281
• feat(core): allow tasks to run with a substring of project name nrwl/nx#29552
• feat(core): add pre and post run apis nrwl/nx#29636 will simplify https://github.com/microsoft/fluentui/blob/master/tools/workspace-plugin/src/executors/build/executor.ts#L15
• feat(js): remove nx property from generated package.json files nrwl/nx#29705
• feat(core): add spinners when graph compute takes long time nrwl/nx#28966