Chore: upgrade packages (#56)

Includes an overall upgrade of major and minor semver versions.

We didn't particularly need the upgrades for features, but some security fixes are included here. So doing an overall upgrade will include those in our distributions. Like the Docker image.

Closes #51, #52, #54

package.json

@@ -6,16 +6,16 @@
     "esm": "^3.2.25",
     "got": "^10.2.2",
     "keyv-fs-sync": "^0.1.0",
-    "mkdirp": "^0.5.1",
-    "sharp": "^0.23.0"
+    "mkdirp": "^1.0.3",
+    "sharp": "^0.25.1"
   },
   "devDependencies": {
     "@babel/cli": "^7.6.2",
     "@babel/core": "^7.6.2",
     "@babel/preset-env": "^7.6.2",
     "@babel/preset-flow": "^7.0.0",
-    "flow-bin": "^0.116.0",
-    "jest": "^24.9.0",
+    "flow-bin": "^0.120.1",
+    "jest": "^25.1.0",
     "prettier": "^1.18.2",
     "rimraf": "^3.0.0"
   },