Fix deprecated use of mocha

The `useColors` option was replaced with `color`.

Author: andyleejordan

test/testRunner.ts

@@ -9,7 +9,7 @@ export function run(): Promise<void> {
     // Create the mocha test
     const mocha = new Mocha({
         ui: "tdd",         // the TDD UI is being used in extension.test.ts (suite, test, etc.)
-        useColors: !process.env.TF_BUILD, // colored output from test results
+        color: !process.env.TF_BUILD, // colored output from test results
         reporter: "mocha-multi-reporters",
         timeout: 5000,
         reporterOptions: {