Bitbucket: fix merge_pull_request. POST`params` --> `data` (#1438)

* Bitbucket: update merge_pull_request method to add merge_message, close_source_branch and merge_strategy parameters

* fix(bitbucket): merge_pull_request params should be data

* fix(bitbucket): support Bitbucket server request

---------

Co-authored-by: Jorge Gómez Zarzosa <jorgegomez@bmat.com>