Jest config adjustmenet to address recent JSDom issue

A recent Renovate merged Jest update caused all tests to start to
fail, due to JSDom security errors. This config adjustment was
recommended in the Jest repo to address this issue.

Relates to:
jestjs/jest#6766 (comment)

package.json

@@ -55,7 +55,8 @@
   "jest": {
     "transform": {
       ".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
-    }
+    },
+    "testURL": "http://localhost"
   },
   "lint-staged": {
     "*.ts*": [