Add build timestamp to the --version output

[per1234]

$ ./arduino-check --version
0.0.0+385b1e8 2020-11-27T04:16:21+00:00

$ ./arduino-check --version --format json
{
  "version": "0.0.0+385b1e8",
  "buildTimestamp": "2020-11-27T04:16:21+00:00"
}

[ubidefeo]

I checked this out and task built but I don't get the timestamp

{
  "version": "0.0.0+d5307a7",
  "buildTimestamp": ""
}

[per1234]

What do you get if you run this command?:

date --utc --iso-8601=second

[ubidefeo]

I get an error for illegal option

date: illegal option -- -
usage: date [-jnRu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

[per1234]

@ubidefeo please try it again now. I have changed the command to be compatible with macOS.

[ubidefeo]

Timestamp showing up correctly
approved