Use core.getBooleanInput

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

__tests__/context.test.ts

@@ -5,6 +5,7 @@ import {getInputs} from '../src/context';
 test('with password and username getInputs does not throw error', async () => {
   process.env['INPUT_USERNAME'] = 'dbowie';
   process.env['INPUT_PASSWORD'] = 'groundcontrol';
+  process.env['INPUT_LOGOUT'] = 'true';
   expect(() => {
     getInputs();
   }).not.toThrowError();