fix(ci): support older Node.js in test matrix

ESLint devDependencies require Node ^20.19.0 || ^22.13.0 ||
>=24, which breaks `yarn install` on older Node versions used
by the prebuildify test matrix. Add `.yarnrc` with
`--ignore-engines true` to skip engine checks.

Also move `yarn install` for test subdirectories from
`test/crashtracker/index.js` into `scripts/test.sh` so
dependencies are installed before Node loads the test file.

Author: watson

.yarnrc

@@ -0,0 +1 @@
+--ignore-engines true

scripts/test.sh

@@ -2,6 +2,12 @@
 set -e
 
 run_test() {
+  local dir
+  dir=$(dirname "$1")
+  if [ -f "${dir}/package.json" ]; then
+    echo "Installing dependencies for $1"
+    yarn --cwd "$dir" install
+  fi
   echo "Running $1"
   node "$1"
 }

test/crashtracker/index.js

@@ -14,8 +14,6 @@ const uid = process.getuid()
 const gid = process.getgid()
 const opts = { cwd, stdio, uid, gid }
 
-execSync('yarn install', opts)
-
 const app = express()
 
 rmSync(path.join(cwd, 'stdout.log'), { force: true })