deps: update node-canvas, Node, + npm audit fix

- update `node-canvas` to latest v3 to work with newer, non-EoL Node versions
  - also less deps like `node-pre-gyp` etc
- update CI matrix to use LTS Node 18+
- run `npm audit fix` after

.github/workflows/ci.yml

@@ -7,15 +7,14 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        # TODO: add back Node 18 once node-canvas is properly supported: https://github.com/Automattic/node-canvas/issues/2025
-        node-version: [16.x] # LTS Node: https://nodejs.org/en/about/releases/
+        node-version: [18.x, 20.x, 22.x] # LTS Node: https://nodejs.org/en/about/releases/
         os: [ubuntu-latest]
 
     steps:
     - name: Checkout repo
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Setup Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node-version }}
         cache: 'npm'