Update tested node version (#329)

Node 12 is end-of-life so I propose to drop it from tests.

Node 18 should be added as the LTS version, and.

Node 19 should replace Node 17 as the current version.

Co-authored-by: Oskari Porkka <oporkka@users.noreply.github.com>

.github/workflows/validation.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [12, 14, 16, 17]
+        node-version: [14, 16, 18, 19]
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v3