remove escape-string-regexp dependency

package.json

@@ -28,7 +28,6 @@
   ],
   "dependencies": {
     "chalk": "2.4.2",
-    "escape-string-regexp": "2.0.0",
     "find-up": "4.1.0",
     "hosted-git-info": "2.7.1",
     "make-fetch-happen": "4.0.1",

updates.js

@@ -206,6 +206,10 @@ function memoize(fn) {
   return arg => cache[arg] || (cache[arg] = fn(arg));
 }
 
+function esc(str) {
+  return str.replace(/[|\\{}()[\]^$+*?.-]/g, "\\$&");
+}
+
 function getAuthAndRegistry(name, registry) {
   if (!name.startsWith("@")) {
     return [registryAuthToken(registry), registry];
@@ -400,7 +404,6 @@ function formatDeps() {
 }
 
 function updatePkg() {
-  const esc = require("escape-string-regexp");
   let newPkgStr = pkgStr;
 
   for (const dep of Object.keys(deps)) {