Added an NVM lock file and adjusted the engine in our package.json to conform

.nvmrc

@@ -0,0 +1 @@
+v10

.travis.yml

@@ -33,7 +33,6 @@ jobs:
     php: 7.4
     env: WP_VERSION=latest WP_MULTISITE=0 RUN_E2E=1
     script:
-      - npm install
       - npm run build:assets
       - npm install jest --global
       - npm run docker:up
@@ -71,8 +70,8 @@ install:
     else
       echo "xdebug.ini does not exist"
     fi
-  - nvm install 10
-  - npm install
+  - nvm install
+  - npm ci
   - composer install --no-dev
   - |
     # Install WP Test suite, install PHPUnit globally:

package.json

@@ -89,8 +89,8 @@
     "wp-textdomain": "1.0.1"
   },
   "engines": {
-    "node": ">=10.15.0",
-    "npm": ">=6.4.1"
+    "node": "^10.22.0",
+    "npm": "^6.14.6"
   },
   "husky": {
     "hooks": {