build: use lts shorthand in GitHub Actions

Rather than hard-coding GitHub Actions to use Node.js 14.x, use the
`lts/*` shorthand for "most recent LTS version".

PR-URL: #39538
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

.github/workflows/auto-start-ci.yml

@@ -10,7 +10,7 @@ on:
     - cron: "*/5 * * * *"
 
 env:
-  NODE_VERSION: 14.x
+  NODE_VERSION: lts/*
 
 jobs:
   startCI:

.github/workflows/commit-lint.yml

@@ -3,7 +3,7 @@ name: "Commit messages adheres to guidelines at https://goo.gl/p2fr5Q"
 on: [pull_request]
 
 env:
-  NODE_VERSION: 14.x
+  NODE_VERSION: lts/*
 
 jobs:
   lint-commit-message:

.github/workflows/commit-queue.yml

@@ -15,7 +15,7 @@ on:
     - cron: "*/5 * * * *"
 
 env:
-  NODE_VERSION: 14.x
+  NODE_VERSION: lts/*
 
 jobs:
   commitQueue:

.github/workflows/daily.yml

@@ -6,7 +6,7 @@ on:
     - cron: "0 0 * * *"
 
 env:
-  NODE_VERSION: 14.x
+  NODE_VERSION: lts/*
 
 jobs:
   build-lto:

.github/workflows/linters.yml

@@ -12,7 +12,7 @@ on:
 
 env:
   PYTHON_VERSION: 3.9
-  NODE_VERSION: 14.x
+  NODE_VERSION: lts/*
 
 jobs:
   lint-addon-docs:

.github/workflows/misc.yml

@@ -11,7 +11,7 @@ on:
       - v[0-9]+.x
 
 env:
-  NODE_VERSION: 14.x
+  NODE_VERSION: lts/*
 
 jobs:
   build-docs: