Update devDependencies and switch to Node.js 16/npm 8

* @babel/core                      ^7.15.5  →   ^7.15.8
* @babel/preset-env                ^7.15.6  →   ^7.15.8
* @rollup/plugin-commonjs          ^20.0.0  →   ^21.0.1
* @rollup/plugin-node-resolve      ^13.0.5  →   ^13.0.6
* autoprefixer                     ^10.3.6  →   ^10.3.7
* babel-plugin-istanbul             ^6.0.0  →    ^6.1.1
* clean-css-cli                     ^5.3.3  →    ^5.4.2
* eslint                           ^7.32.0  →    ^8.0.0
* eslint-config-xo                 ^0.38.0  →   ^0.39.0
* eslint-plugin-import             ^2.24.2  →   ^2.25.1
* eslint-plugin-qunit               ^6.2.0  →    ^7.0.0
* eslint-plugin-unicorn            ^36.0.0  →   ^37.0.1
* karma                             ^6.3.4  →    ^6.3.5
* linkinator                       ^2.14.0  →   ^2.14.4
* nodemon                          ^2.0.13  →   ^2.0.14
* postcss                           ^8.3.8  →   ^8.3.11
* postcss-cli                       ^9.0.0  →    ^9.0.1
* rollup                           ^2.57.0  →   ^2.58.0
* stylelint-config-twbs-bootstrap   ^2.2.3  →    ^2.2.4
* vnu-jar                           21.9.2  →  21.10.12

.github/workflows/browserstack.yml

@@ -5,7 +5,7 @@ on:
 
 env:
   FORCE_COLOR: 2
-  NODE: 14
+  NODE: 16
 
 jobs:
   browserstack:

.github/workflows/bundlewatch.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   FORCE_COLOR: 2
-  NODE: 14
+  NODE: 16
 
 jobs:
   bundlewatch:

.github/workflows/css.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   FORCE_COLOR: 2
-  NODE: 14
+  NODE: 16
 
 jobs:
   css:

.github/workflows/dart-sass.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   FORCE_COLOR: 2
-  NODE: 14
+  NODE: 16
 
 jobs:
   css:

.github/workflows/docs.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   FORCE_COLOR: 2
-  NODE: 14
+  NODE: 16
 
 jobs:
   docs:

.github/workflows/js.yml

@@ -40,7 +40,7 @@ jobs:
 
       - name: Run Coveralls
         uses: coverallsapp/github-action@1.1.3
-        if: matrix.node == 14
+        if: matrix.node == 16
         with:
           github-token: "${{ secrets.GITHUB_TOKEN }}"
           path-to-lcov: "./js/coverage/lcov.info"

.github/workflows/lint.yml

@@ -8,7 +8,7 @@ on:
 
 env:
   FORCE_COLOR: 2
-  NODE: 14
+  NODE: 16
 
 jobs:
   lint: