fix: upgrade ignore from 5.1.4 to 5.1.8 (#36)

Snyk has created this PR to upgrade ignore from 5.1.4 to 5.1.8.

See this package in npm:
https://www.npmjs.com/package/ignore

See this project in Snyk:
https://app.snyk.io/org/jjmschofield/project/b82e5760-b938-4d01-9c5b-77b7d2564e99?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -26,7 +26,7 @@
   },
   "dependencies": {
     "commander": "^4.1.1",
-    "ignore": "^5.1.4"
+    "ignore": "^5.1.8"
   },
   "devDependencies": {
     "@types/jest": "^26.0.5",