Bump tslint from 5.18.0 to 5.20.0

Bumps [tslint](https://github.com/palantir/tslint) from 5.18.0 to 5.20.0.
- [Release notes](https://github.com/palantir/tslint/releases)
- [Changelog](https://github.com/palantir/tslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/palantir/tslint/compare/5.18.0...5.20.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package-lock.json

@@ -6479,16 +6479,16 @@
       "dev": true
     },
     "tslint": {
-      "version": "5.18.0",
+      "version": "5.20.0",
-      "resolved": "https://registry.npmjs.org/tslint/-/tslint-5.18.0.tgz",
+      "resolved": "https://registry.npmjs.org/tslint/-/tslint-5.20.0.tgz",
-      "integrity": "sha512-Q3kXkuDEijQ37nXZZLKErssQVnwCV/+23gFEMROi8IlbaBG6tXqLPQJ5Wjcyt/yHPKBC+hD5SzuGaMora+ZS6w==",
+      "integrity": "sha512-2vqIvkMHbnx8acMogAERQ/IuINOq6DFqgF8/VDvhEkBqQh/x6SP0Y+OHnKth9/ZcHQSroOZwUQSN18v8KKF0/g==",
       "dev": true,
       "requires": {
         "@babel/code-frame": "^7.0.0",
         "builtin-modules": "^1.1.1",
         "chalk": "^2.3.0",
         "commander": "^2.12.1",
-        "diff": "^3.2.0",
+        "diff": "^4.0.1",
         "glob": "^7.1.1",
         "js-yaml": "^3.13.1",
         "minimatch": "^3.0.4",
@@ -6499,12 +6499,6 @@
         "tsutils": "^2.29.0"
       },
       "dependencies": {
-        "diff": {
-          "version": "3.5.0",
-          "resolved": "https://registry.npmjs.org/diff/-/diff-3.5.0.tgz",
-          "integrity": "sha512-A46qtFgd+g7pDZinpnwiRJtxbC1hpgf0uzP3iG89scHk0AUC7A1TGxf5OiiOUv/JMZR8GOt8hL900hV0bOy5xA==",
-          "dev": true
-        },
         "tsutils": {
           "version": "2.29.0",
           "resolved": "https://registry.npmjs.org/tsutils/-/tsutils-2.29.0.tgz",

package.json

@@ -47,6 +47,6 @@
   },
   "devDependencies": {
     "tslint-config-dabapps": "github:dabapps/tslint-config-dabapps#v0.5.5",
-    "tslint": "5.18.0"
+    "tslint": "5.20.0"
   }
 }