Bump dev Node to LTS (22) and start testing on it

Bumping the development version of Node to 22 specifically allows us to
upgrade to Yarn v4.

Author: mcmire

.github/workflows/build-test.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        node-version: [18.x, 20.x]
+        node-version: [18.x, 20.x, 22.x]
     steps:
       - uses: actions/checkout@v4
       - name: Use Node.js ${{ matrix.node-version }}

.nvmrc

@@ -1 +1 @@
-v18
+lts/*