Enable nullable annotations in update-dependencies project

[lbussell]

Related: #5006, #6114 (comment)

[richlander]

This code is subject to out of bounds exception, yes?

dotnet-docker/eng/update-dependencies/ChiselUpdater.cs

Line 95 in be05cf5

string sha = content.Split(" ")[0];

[lbussell]

This code is subject to out of bounds exception, yes?

dotnet-docker/eng/update-dependencies/ChiselUpdater.cs

Line 95 in be05cf5

string sha = content.Split(" ")[0];

How so?

If we get an unexpected result from the Chisel checksum file, that doesn't have a double-space " " in it, then string.Split will return an array of one string (the input string). Or am I looking at the wrong thing?

https://sharplab.io/#v2:EYLgtghglgdgNAFxAJwK7wCYgNQB8ACATAIwCwAUAG4TIAEAzrQLy0BErA3BdXfsQAyMW9AHQBlAA4AbKAgAUrWmwCUAbX4BdLuT4BOOX0HNhyjkA===

[richlander]

Ah. I forgot/didn't realize that string.split worked that way. Makes sense.