Update to 0.18.0 (#77)

Co-authored-by: pham <723522+pham@users.noreply.github.com>

Author: github-actions[bot]

askclass-course-theme.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
   spec.name          = "askclass-course-theme"
-  spec.version       = "0.17.0"
+  spec.version       = "0.18.0"
   spec.authors       = ["AskClass"]
   spec.email         = ["team@askclass.com"]