fix: upgrade shescape to v2.1.0

shescape below v2 have been marked as deprecated. This
change updates to the new interface. Please validate
these changes against the migration document:
https://github.com/ericcornelissen/shescape/blob/HEAD/docs/migration.md

Author: thisislawatts

lib/sub-process.ts

@@ -1,5 +1,5 @@
 import * as childProcess from 'child_process';
-import { quoteAll } from 'shescape';
+import { quoteAll } from 'shescape/stateless';
 
 export function execute(
   command: string,

package.json

@@ -34,7 +34,7 @@
     "@snyk/cli-interface": "^2.11.0",
     "@snyk/cocoapods-lockfile-parser": "3.6.2",
     "@snyk/dep-graph": "^1.23.1",
-    "shescape": "1.6.1",
+    "shescape": "2.1.0",
     "source-map-support": "^0.5.7",
     "tslib": "^2.0.0"
   },