Add status code 100 as valid GitHub post response

[mrrobot47]

While using vip-go-ci in GitHub actions via action-phpcs-code-review, recently we started getting an additional comment along with the requested changes from phpcs scan done by vip-go-ci:

GitHub API communication error. Please contact a human. (commit-ID: <id>).

On debugging $resp_headers when the post request to submit review comments was done,

the following dump was obtained.

array(24) {
  ["status"]=>
  array(1) {
    [0]=>
    string(3) "100"
  }
  ["server"]=>
  array(1) {
    [0]=>
    string(10) "GitHub.com"
  }
  ["date"]=>
  array(1) {
    [0]=>
    string(29) "Thu, 11 Mar 2021 11:33:16 GMT"
  }
  ["content-type"]=>
  array(1) {
    [0]=>
    string(31) "application/json; charset=utf-8"
  }
  ["content-length"]=>
  array(1) {
    [0]=>
    string(4) "1766"
  }
  ["cache-control"]=>
  array(1) {
    [0]=>
    string(32) "private, max-age=60, s-maxage=60"
  }
  ["vary"]=>
  array(2) {
    [0]=>
    string(43) "Accept, Authorization, Cookie, X-GitHub-OTP"
    [1]=>
    string(41) "Accept-Encoding, Accept, X-Requested-With"
  }
  ["etag"]=>
  array(1) {
    [0]=>
    string(66) ""<redacted>""
  }
  ["x-oauth-scopes"]=>
  array(1) {
    [0]=>
    string(32) "repo, workflow, write:discussion"
  }
  ["x-accepted-oauth-scopes"]=>
  array(1) {
    [0]=>
    string(0) ""
  }
  ["x-github-media-type"]=>
  array(1) {
    [0]=>
    string(22) "github.v3; format=json"
  }
  ["x-ratelimit-limit"]=>
  array(1) {
    [0]=>
    string(4) "5000"
  }
  ["x-ratelimit-remaining"]=>
  array(1) {
    [0]=>
    string(4) "4924"
  }
  ["x-ratelimit-reset"]=>
  array(1) {
    [0]=>
    string(10) "1615464816"
  }
  ["x-ratelimit-used"]=>
  array(1) {
    [0]=>
    string(2) "76"
  }
  ["access-control-expose-headers"]=>
  array(1) {
    [0]=>
    string(226) "ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Used, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, Deprecation, Sunset"
  }
  ["access-control-allow-origin"]=>
  array(1) {
    [0]=>
    string(1) "*"
  }
  ["strict-transport-security"]=>
  array(1) {
    [0]=>
    string(44) "max-age=31536000; includeSubdomains; preload"
  }
  ["x-frame-options"]=>
  array(1) {
    [0]=>
    string(4) "deny"
  }
  ["x-content-type-options"]=>
  array(1) {
    [0]=>
    string(7) "nosniff"
  }
  ["x-xss-protection"]=>
  array(1) {
    [0]=>
    string(13) "1; mode=block"
  }
  ["referrer-policy"]=>
  array(1) {
    [0]=>
    string(57) "origin-when-cross-origin, strict-origin-when-cross-origin"
  }
  ["content-security-policy"]=>
  array(1) {
    [0]=>
    string(18) "default-src 'none'"
  }
  ["x-github-request-id"]=>
  array(1) {
    [0]=>
    string(32) "<redacted>"
  }
}

The received status code was 100, leading to failure in this condition and that is why the comment with the error was getting posted.

The HTTP 100 Continue informational status response code indicates that everything so far is OK and that the client should continue with the request or ignore it if it is already finished.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/100

With this patch, vip-go-ci started working normally as before in GitHub actions. Please let me know if this is the right way forward or if any other changes are needed.

[gudmdharalds]

Thank you for the contribution! This looks good.

[gudmdharalds]

Added to changelog in #178.