Fix overriding request options from @actions/github

[luketomlinson]

Problem

Since introducing retries in #288, we would override the request field of the OctokitOptions we pass into the getOctokit method. The problem is that the @actions/github package also provides some defaults for the request field. source. Some users rely on these defaults and would break since we added retries.

Behavior:

If we have these defaults:

{
  request: {
    agent: 'some-agent'
  }
}

and add these options:

{
  request: {
    retries: 2
  }
}

we get the following output:

{
  request: {
    retries: 2
  }
}

Note the original options are completely overriden, which is not desired.

Solution

We copy the default options.request fields from the @actions/github package into the request field when we add the retries field.

Fixed behavior:

if we have these defaults:

{
  request: {
    agent: 'some-agent'
  }
}

and add these options:

{
  request: {
    retries: 2
  }
}

we get the following output:

{
  request: {
    agent: 'some-agent',
    retries: 2
  }
}

fixes #291