fix: upgrade underscore.string and add snyk patch

.snyk

@@ -1,5 +1,5 @@
 # Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
-version: v1.7.1
+version: v1.13.1
 # ignores vulnerabilities until expiry date; change duration by modifying expiry date
 ignore:
   'npm:marked:20170907':

package.json

@@ -20,12 +20,12 @@
     "backstop-test": "backstop test",
     "backstop-reference": "backstop reference",
     "backstop-test-local": "grunt build && grunt clean && npm run backstop-reference && npm run backstop-test",
-    "test": "echo 'No unit tests. Please see readme for backstop instructions if running this manually.'",
     "snyk-protect": "snyk protect",
     "prepublish": "npm run snyk-protect"
   },
   "dependencies": {
-    "susy": "^2.2.12"
+    "susy": "^2.2.12",
+    "underscore.string": "3.3.5"
   },
   "devDependencies": {
     "autoprefixer": "^7.1.1",
@@ -84,4 +84,4 @@
     "last 3 versions"
   ],
   "snyk": true
-}
+}

yarn.lock

@@ -7075,6 +7075,10 @@ split@0.3:
   dependencies:
     through "2"
 
+sprintf-js@^1.0.3:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.1.1.tgz#36be78320afe5801f6cea3ee78b6e5aab940ea0c"
+
 sprintf-js@~1.0.2:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.0.3.tgz#04e6926f662895354f3dd015203633b857297e2c"
@@ -7694,6 +7698,13 @@ undefsafe@^2.0.0:
   dependencies:
     debug "^2.2.0"
 
+underscore.string@3.3.5:
+  version "3.3.5"
+  resolved "https://registry.yarnpkg.com/underscore.string/-/underscore.string-3.3.5.tgz#fc2ad255b8bd309e239cbc5816fd23a9b7ea4023"
+  dependencies:
+    sprintf-js "^1.0.3"
+    util-deprecate "^1.0.2"
+
 underscore.string@~2.2.0rc:
   version "2.2.1"
   resolved "https://registry.yarnpkg.com/underscore.string/-/underscore.string-2.2.1.tgz#d7c0fa2af5d5a1a67f4253daee98132e733f0f19"
@@ -7803,7 +7814,7 @@ use@^3.1.0:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/use/-/use-3.1.1.tgz#d50c8cac79a19fbc20f2911f56eb973f4e10070f"
 
-util-deprecate@~1.0.1:
+util-deprecate@^1.0.2, util-deprecate@~1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/util-deprecate/-/util-deprecate-1.0.2.tgz#450d4dc9fa70de732762fbd2d4a28981419a0ccf"