Bump rack-cors from 2.0.1 to 2.0.2 in /backend

Bumps [rack-cors](https://github.com/cyu/rack-cors) from 2.0.1 to 2.0.2.
- [Changelog](https://github.com/cyu/rack-cors/blob/master/CHANGELOG.md)
- [Commits](cyu/rack-cors@v2.0.1...v2.0.2)

---
updated-dependencies:
- dependency-name: rack-cors
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/Gemfile

@@ -60,7 +60,7 @@ gem "ruby-progressbar", require: false
 
 gem "kaminari-actionview"
 gem "kaminari-mongoid"
-gem "rack-cors", "2.0.1", require: "rack/cors" # freezing to gemfile.lock version because heroku is not respecting lockfile
+gem "rack-cors", "2.0.2", require: "rack/cors" # freezing to gemfile.lock version because heroku is not respecting lockfile
 gem "simplecov", require: false, group: :test
 
 group :development, :test do

backend/Gemfile.lock

@@ -308,7 +308,7 @@ GEM
     pusher-signature (0.1.8)
     racc (1.7.3)
     rack (2.2.9)
-    rack-cors (2.0.1)
+    rack-cors (2.0.2)
       rack (>= 2.0.0)
     rack-test (2.1.0)
       rack (>= 1.3)
@@ -499,7 +499,7 @@ DEPENDENCIES
   pry-rails
   puma (= 5.6.8)
   pusher
-  rack-cors (= 2.0.1)
+  rack-cors (= 2.0.2)
   rack-timeout
   rails (~> 6.1.7.6)
   rails_12factor