gitignore - properly ignore nuget config files (#4192)

# Description of Changes

Ignoring nuget config files regardless of casing, as well as in the root
directory since we generate them there now.

# API and ABI breaking changes

None.

# Expected complexity level and risk

1

# Testing

- [x] Files generated by `write-nuget-config.sh` are now properly
ignored

---------

Co-authored-by: Zeke Foppa <bfops@users.noreply.github.com>

Author: bfops

.gitignore

@@ -238,3 +238,6 @@ venv/
 
 # Windows null device artifact
 nul
+
+[Nn][Uu][Gg][Ee][Tt].[Cc][Oo][Nn][Ff][Ii][Gg]
+[Nn][Uu][Gg][Ee][Tt].[Cc][Oo][Nn][Ff][Ii][Gg].meta

sdks/csharp/.gitignore

@@ -73,8 +73,8 @@ bin~
 obj~
 
 # This is used for local paths to SpacetimeDB packages.
-/nuget.config
-/nuget.config.meta
+[Nn][Uu][Gg][Ee][Tt].config
+[Nn][Uu][Gg][Ee][Tt].config.meta
 .idea/
 
 # Hydrated SDK DLLs (produced by `cargo ci dlls`)