Use Nodejs 18+ in CI

Node 18 is required to run out generator because of the the v6.0.0 release of
css-minimizer-webpack-plugin package.

.circleci/config.yml

@@ -3,7 +3,7 @@ version: 2
 
 aliases:
   - &docker-image
-    - image: circleci/ruby:3.0-node-browsers
+    - image: cimg/ruby:3.0-browsers
 
   # Print critical data and executables versions.
   - &print-system-info

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         ruby: [3.0, 3.3]
-        node: [16, 20]
+        node: [18, 20]
     runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@v4
@@ -84,7 +84,7 @@ jobs:
     strategy:
       matrix:
         ruby: [3.0, 3.3]
-        node: [16, 20]
+        node: [18, 20]
         rake_task: ['run_rspec:all_but_examples', 'run_rspec:examples']
     runs-on: ubuntu-22.04
     steps:

.github/workflows/package-js-tests.yml

@@ -11,7 +11,7 @@ jobs:
   build:
     strategy:
       matrix:
-        node: [16, 20]
+        node: [18, 20]
     runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@v4

.github/workflows/rspec-package-specs.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         ruby: [3.0, 3.3]
-        node: [16, 20]
+        node: [18, 20]
     runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@v4