docker: do not set undefined args for checking availability

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

__tests__/docker.test.ts

@@ -52,7 +52,7 @@ describe('isAvailable', () => {
     const execSpy = jest.spyOn(Exec, 'getExecOutput');
     await Docker.isAvailable();
     // eslint-disable-next-line jest/no-standalone-expect
-    expect(execSpy).toHaveBeenCalledWith(`docker`, undefined, {
+    expect(execSpy).toHaveBeenCalledWith(`docker`, [], {
       silent: true,
       ignoreReturnCode: true
     });

src/docker.ts

@@ -25,7 +25,7 @@ export class Docker {
   }
 
   public static async isAvailable(): Promise<boolean> {
-    const ok: boolean = await Exec.getExecOutput('docker', undefined, {
+    const ok: boolean = await Exec.getExecOutput('docker', [], {
       ignoreReturnCode: true,
       silent: true
     })