ci: align e2e-webapp-auth-full pnpm pin with root packageManager

The workflow pinned pnpm 10.23.0; root package.json declares 10.33.2.
pnpm/action-setup v4+ now rejects the conflict (root + workflow are
both 'specified versions' as far as the action is concerned), failing
the job before it can run any tests. Bump to v5.0.0 of the action and
match the 10.33.2 pin already used by unit-tests-webapp.yml and
release.yml.

Author: matt-aitken

.github/workflows/e2e-webapp-auth-full.yml

@@ -74,9 +74,9 @@ jobs:
           fetch-depth: 0
 
       - name: ⎔ Setup pnpm
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@fc06bc1257f339d1d5d8b3a19a8cae5388b55320 # v5.0.0
         with:
-          version: 10.23.0
+          version: 10.33.2
 
       - name: ⎔ Setup node
         uses: buildjet/setup-node@v4