Drop Node 10 support for ESM (#5303)

This change is a part of the next major version (v14).

- Remove Node 10 from CI
- Update `engines.node`

In addition, this removes needless `CI: true` (just a refactoring).
See <https://github.blog/changelog/2020-04-15-github-actions-sets-the-ci-environment-variable-to-true/>

.github/workflows/linting.yml

@@ -9,9 +9,6 @@ on:
     branches:
       - '**'
 
-env:
-  CI: true
-
 jobs:
   lint:
     name: Lint on Node.js ${{ matrix.node }} and ${{ matrix.os }}

.github/workflows/testing.yml

@@ -9,9 +9,6 @@ on:
     branches:
       - '**'
 
-env:
-  CI: true
-
 jobs:
   test:
     name: Test on Node.js ${{ matrix.node }} and ${{ matrix.os }}
@@ -21,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node: [10, 12, 14, 16]
+        node: [12, 14, 16]
         os: [ubuntu-latest, windows-latest, macos-latest]
         exclude:
           - os: ubuntu-latest

package.json

@@ -191,6 +191,6 @@
     "typescript": "^4.2.4"
   },
   "engines": {
-    "node": ">=10.13.0"
+    "node": "^12.20.0 || ^14.13.1 || >=16.0.0"
   }
 }