Add Ruby 3.0 support (#16046)

* Fix issues with POSIX::Spawn, Terrapin and Ruby 3.0

Also improve the Terrapin monkey-patch for the stderr/stdout issue.

* Fix keyword argument handling throughout the codebase

* Monkey-patch Paperclip to fix keyword arguments handling in validators

* Change validation_extensions to please CodeClimate

* Bump microformats from 4.2.1 to 4.3.1

* Allow Ruby 3.0

* Add Ruby 3.0 test target to CircleCI

* Add test for admin dashboard warnings

* Fix admin dashboard warnings on Ruby 3.0

.circleci/config.yml

@@ -129,6 +129,13 @@ jobs:
         environment: *ruby_environment
     <<: *install_ruby_dependencies
 
+  install-ruby3.0:
+    <<: *defaults
+    docker:
+      - image: circleci/ruby:3.0-buster-node
+        environment: *ruby_environment
+    <<: *install_ruby_dependencies
+
   build:
     <<: *defaults
     steps:
@@ -187,6 +194,18 @@ jobs:
       - image: circleci/redis:5-alpine
     <<: *test_steps
 
+  test-ruby3.0:
+    <<: *defaults
+    docker:
+      - image: circleci/ruby:3.0-buster-node
+        environment: *ruby_environment
+      - image: circleci/postgres:12.2
+        environment:
+          POSTGRES_USER: root
+          POSTGRES_HOST_AUTH_METHOD: trust
+      - image: circleci/redis:5-alpine
+    <<: *test_steps
+
   test-webui:
     <<: *defaults
     docker:
@@ -227,6 +246,10 @@ workflows:
           requires:
             - install
             - install-ruby2.7
+      - install-ruby3.0:
+          requires:
+            - install
+            - install-ruby2.7
       - build:
           requires:
             - install-ruby2.7
@@ -241,6 +264,10 @@ workflows:
           requires:
             - install-ruby2.6
             - build
+      - test-ruby3.0:
+          requires:
+            - install-ruby3.0
+            - build
       - test-webui:
           requires:
             - install