Move to a supported Node LTS (#416)

Node 18 (LTS/Hydrogen) went EOL in October 2023 and loses its security support in April 2025.

Node 22 was promoted to an LTS release in October 2024, and we should probably move over.

Author: lewisgoddard

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [16.x, 18.x]
+        node-version: [18.x, 20.x, 22.x]
 
     steps:
     - uses: actions/checkout@v4
@@ -49,7 +49,7 @@ jobs:
     - name: Install the dependencies
       run: |
         export DEBIAN_FRONTEND=noninteractive
-        curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
+        curl -fsSL https://deb.nodesource.com/setup_22.x | sudo -E bash -
         sudo apt-get update -y
         sudo apt-get install -y --no-install-recommends software-properties-common
         sudo add-apt-repository -y ppa:vala-team/daily