Bump Node.js from 14 to 18

Use latest long term support (LTS) version of Node.js for tests and
publishing. Also use the new version 2 lockfile format for current
versions of npm.

Author: lfdebrux

.github/workflows/publish.yaml

@@ -46,10 +46,10 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - uses: actions/setup-node@v2
+      - uses: actions/setup-node@v3
         with:
+          node-version-file: '.nvmrc'
           cache: 'npm'
-          node-version: '14'
 
       - uses: ruby/setup-ruby@v1
         with:

.github/workflows/test.yaml

@@ -10,9 +10,9 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - uses: actions/setup-node@v2
+      - uses: actions/setup-node@v3
         with:
-          node-version: '14'
+          node-version-file: '.nvmrc'
           cache: 'npm'
 
       - uses: ruby/setup-ruby@v1

.nvmrc

@@ -1 +1 @@
-14
+18