fix(deps): update dependency execa to v5 (#81)

Author: renovate[bot]

package-lock.json

@@ -18,7 +18,7 @@
   "dependencies": {
     "@semantic-release/error": "^2.2.0",
     "aggregate-error": "^3.0.0",
-    "execa": "^4.0.0",
+    "execa": "^5.0.0",
     "npm": "^6.4.1",
     "read-pkg": "^5.0.0"
   },