feat: use latest @snyk/fix with child_process package

Use latest @snyk/fix package that has the child_process functionality separated into it's own package. No changes in behaviour.

package.json

@@ -75,7 +75,7 @@
     "@snyk/cloud-config-parser": "^1.9.2",
     "@snyk/code-client": "3.7.0",
     "@snyk/dep-graph": "^1.27.1",
-    "@snyk/fix": "1.601.0",
+    "@snyk/fix": "1.620.0",
     "@snyk/gemfile": "1.2.0",
     "@snyk/graphlib": "^2.1.9-patch.3",
     "@snyk/inquirer": "^7.3.3-patch",