test: cap root Jest worker usage

Limit root Jest parallelism so native-heavy test runs stay usable on developer machines and shared CI hosts.

Author: oetr

package.json

@@ -25,9 +25,9 @@
 		"test:default": "npm run test:jest",
 		"test:linux:darwin": "npm run test:jest && cd tests && sh ../scripts/run_all.sh fuzz",
 		"test:win32": "npm run test:jest && cd tests && ..\\scripts\\run_all.bat fuzz",
-		"test:jest": "jest && npm run test --ws --if-present",
-		"test:jest:coverage": "jest --coverage",
-		"test:jest:watch": "jest --watch",
+		"test:jest": "jest --maxWorkers=25% && npm run test --ws --if-present -- --maxWorkers=25%",
+		"test:jest:coverage": "jest --coverage --maxWorkers=25%",
+		"test:jest:watch": "jest --watch --maxWorkers=25%",
 		"example": "run-script-os",
 		"example:linux:darwin": "cd examples && sh ../scripts/run_all.sh dryRun",
 		"example:win32": "cd examples && ..\\scripts\\run_all.bat dryRun",