[Tests] add npm run lint

Author: ljharb

.eslintrc

@@ -0,0 +1,5 @@
+{
+	"root": true,
+
+	"extends": "@ljharb",
+}

package.json

@@ -7,6 +7,8 @@
 		"./package.json": "./package.json"
 	},
 	"scripts": {
+		"lint": "eslint --ext=.js,.mjs .",
+		"pretest": "npm run lint",
 		"test": "echo \"Error: no test specified\" && exit 1"
 	},
 	"repository": {
@@ -27,5 +29,9 @@
 	"bugs": {
 		"url": "https://github.com/inspect-js/is-shared-array-buffer/issues"
 	},
-	"homepage": "https://github.com/inspect-js/is-shared-array-buffer#readme"
+	"homepage": "https://github.com/inspect-js/is-shared-array-buffer#readme",
+	"devDependencies": {
+		"@ljharb/eslint-config": "^17.5.1",
+		"eslint": "^7.21.0"
+	}
 }