fix(web-ext-lint): ensure Node.js is installed

When use_standalone_web_ext was true, the ensure-web-ext role checks
whether Node.js is installed, but this wasn't the case when it was
false. This commit fixes this by always running ensure-nodejs-fork.

Change-Id: I538cb3430c2994fc9615f2ffe998c4cd95ec07d4
diff --git a/playbooks/web-ext-lint/pre.yaml b/playbooks/web-ext-lint/pre.yaml
index 37d845b..3fee91c 100644
--- a/playbooks/web-ext-lint/pre.yaml
+++ b/playbooks/web-ext-lint/pre.yaml
@@ -1,5 +1,10 @@
 - hosts: all
   tasks:
+    - name: Ensure NodeJS is installed
+      include_role:
+        name: ensure-nodejs-fork
+      vars:
+        node_version: 20
     - name: Ensure web-ext is installed
       include_role:
         name: ensure-web-ext