Fix incompatibility with older node versions

Author: pilafmon

package.json

@@ -87,12 +87,12 @@
    "devDependencies": {
       "@types/node": "~17.0",
       "@types/through2": "~2.0",
-      "@typescript-eslint/eslint-plugin": "~5.14",
-      "@typescript-eslint/parser": "~5.14",
+      "@typescript-eslint/eslint-plugin": "~5.15",
+      "@typescript-eslint/parser": "~5.15",
       "add-dist-header": "~0.1",
       "assert-deep-strict-equal": "~1.0",
-      "cpy-cli": "~4.0",
-      "eslint": "~8.10",
+      "cpy-cli": "~4.1",
+      "eslint": "~8.11",
       "jshint": "~2.13",
       "mocha": "~9.2",
       "npm-run-all2": "~5.0",

tsconfig.json

@@ -1,6 +1,6 @@
 {
    "compilerOptions": {
-      "target": "ES2020",
+      "target": "ES2015",
       "module": "ES2020",
       "moduleResolution": "node",
       "declaration": true,