TAP reports can't be appended if there are failed tests

[jcamiel]

TAP reports can't be appended if there are failed tests:

$ hurl --test --report-tap build/result.tap tests_ok/test.1.hurl tests_ok/test.2.hurl
$ hurl --test --report-tap build/result.tap tests_ok/test.3.hurl
tests_ok/test.1.hurl: Running [1/2]
tests_ok/test.1.hurl: Success (1 request(s) in 8 ms)
tests_ok/test.2.hurl: Running [2/2]
error: Assert body value
  --> tests_ok/test.2.hurl:8:1
   |
 8 | `Goodbye World!`
   | ^^^^^^^^^^^^^^^^ actual value is <Hello World!>
   |

tests_ok/test.2.hurl: Failure (2 request(s) in 2 ms)
write tap report build/result.tap
--------------------------------------------------------------------------------
Executed files:  2
Succeeded files: 1 (50.0%)
Failed files:    1 (50.0%)
Duration:        19 ms

tests_ok/test.3.hurl: Running [1/1]
tests_ok/test.3.hurl: Success (1 request(s) in 4 ms)
write tap report build/result.tap
error: Invalid TAP line <not ok 2 - tests_ok/test.2.hurl> - must start with ok or nok
1..2
ok 1 - tests_ok/test.1.hurl
not ok 2 - tests_ok/test.2.hurl

Thanks @msinton