Fix tests

[zhibek]

I want to contribute to this reporter, but after setting up the repo locally I found yarn test (npm run test) was failing with the following output:

$ mocha -r ts-node/register ./tests/*.ts

/home/john/Sites/wdio-timeline-reporter/node_modules/ts-node/src/index.ts:293
    return new TSError(diagnosticText, diagnosticCodes)
           ^
TSError: ⨯ Unable to compile TypeScript:
lib/timeline-reporter.ts:60:11 - error TS2345: Argument of type 'ReporterOptions' is not assignable to parameter of type 'Options'.
  Type 'ReporterOptions' is missing the following properties from type 'Options': configFile, logFile, logLevel

60     super(options);
             ~~~~~~~
lib/timeline-reporter.ts:91:3 - error TS2416: Property 'onRunnerEnd' in type 'TimelineReporter' is not assignable to the same property in base type 'Reporter'.
  Type '(runner: any) => void' is not assignable to type '() => void'.

91   onRunnerEnd(runner) {
     ~~~~~~~~~~~

I've committed these temporary "fixes" to allow tests to pass. Real fixes will require more in depth experience of WDIO reporter interface. If I gain this experience I'll commit real fixes, if not I leave this open for the community.