[repo] Add dependabot.yml to solution (open-telemetry#6028)

Author: CodeBlanch

OpenTelemetry.sln

@@ -74,6 +74,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".github", ".github", "{F1D0
 	ProjectSection(SolutionItems) = preProject
 		.github\codecov.yml = .github\codecov.yml
 		.github\CODEOWNERS = .github\CODEOWNERS
+		.github\dependabot.yml = .github\dependabot.yml
 		.github\PULL_REQUEST_TEMPLATE.md = .github\PULL_REQUEST_TEMPLATE.md
 	EndProjectSection
 EndProject