fix: Update project name in solution file (#380)

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## This PR
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This pull request includes a small change to the `OpenFeature.sln` file.
The change renames the project from `"."` to `".root"` to fix the
current build issues.

*
[`OpenFeature.sln`](diffhunk://#diff-3043b3423bc4a34abd4501e344ea4f1f3c18a61e3ca97b9f914a868fa20105b6L6-R6):
Renamed project from `"."` to `".root"` to improve clarity.

### Notes
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- Check build for details:
https://github.com/open-feature/dotnet-sdk/actions/runs/13279965378/job/37076213831

Signed-off-by: André Silva <[email protected]>

Author: askpt

OpenFeature.sln

@@ -3,7 +3,7 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
 VisualStudioVersion = 17.4.33213.308
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".", ".", "{E8916D4F-B97E-42D6-8620-ED410A106F94}"
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".root", ".root", "{E8916D4F-B97E-42D6-8620-ED410A106F94}"
 	ProjectSection(SolutionItems) = preProject
 		README.md = README.md
 		CONTRIBUTING.md = CONTRIBUTING.md