Update fog-core requirement from >= 1.35, < 2.1.1 to >= 1.35, < 2.6.1 (#112)

Updates the requirements on [fog-core](https://github.com/fog/fog-core) to permit the latest version.
- [Changelog](https://github.com/fog/fog-core/blob/master/changelog.md)
- [Commits](fog/fog-core@v1.35.0...v2.6.0)

---
updated-dependencies:
- dependency-name: fog-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Signed-off-by: Corey Hemminger <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Corey Hemminger <[email protected]>

Author: dependabot[bot]

kitchen-rackspace.gemspec

@@ -20,6 +20,6 @@ Gem::Specification.new do |spec|
   spec.required_ruby_version = ">= 3.1"
 
   spec.add_dependency "fog-rackspace", "~> 0.1.6"
-  spec.add_dependency "fog-core", ">= 1.35" ,"< 2.1.1"
+  spec.add_dependency "fog-core", ">= 1.35", "< 2.6.1"
   spec.add_dependency "test-kitchen", ">= 1.1", "< 5.0"
 end