Ensure CircleCI configuration is up-to-date

This change:

- Ensures that browser tools for running feature tests are explicitly
  available.
- Ensures that all required executors use Ruby 3. (Ruby 2 is now EOL.)

.circleci/config.yml

@@ -1,6 +1,9 @@
 version: 2.1
 
 orbs:
+  # Browser tools are required for feature specs.
+  browser-tools: circleci/[email protected]
+
   # Always take the latest version of the orb, this allows us to
   # run specs against Solidus supported versions only without the need
   # to change this configuration every time a Solidus version is released
@@ -9,11 +12,15 @@ orbs:
 
 jobs:
   run-specs-with-postgres:
-    executor: solidusio_extensions/postgres
+    executor:
+      name: solidusio_extensions/postgres
+      ruby_version: "3.0"
     steps:
       - solidusio_extensions/run-tests
   run-specs-with-mysql:
-    executor: solidusio_extensions/mysql
+    executor:
+      name: solidusio_extensions/mysql
+      ruby_version: "3.0"
     steps:
       - solidusio_extensions/run-tests