v5.x doesn't work with some providers

[HitkoDev]

Describe the bug
Some OAuth providers (notably login.microsoftonline.com) don't accept requests with Transfer-encoding: chunked, which is the default behaviour in NodeJS unless content-length header is provided.

To Reproduce
Steps to reproduce the behaviour:

    request(
        {
            form: { * payload * },
            method: 'POST',
            url: 'https://login.microsoftonline.com/common/oauth2/v2.0/token',
            headers: {},
        }
    )

Expected behaviour
Returns request response.

Actual behaviour
Throws OPError: expected 200 OK, got: 404 Not Found.

Environment:

• openid-client version: v5.x.x
• node version: all

Additional context
This was introduced by removing got dependency which took care of setting content-length header.

• the bug is happening on latest openid-client too.
• i have searched the issues tracker on github for similar issues and couldn't find anything related.

[panva]

@HitkoDev thank you for bringing it up, i'll try and fix it promptly.