Ability to automatically resolve merge conflicts with a .gittattributes file

In a pull request I would like Bitbucket to automatically resolve merge conflicts on a specific file such that it always takes the version in the pull request. We have a release notes file that we update with each branch we deliver. We always want the version being delivered. Since it is always changing it often results in a merge conflict when two pull requests are happening at the same time.

In the .gittattributes file you can set a merge rule to override the default merge algorithm. For example the following rule will always take the version from "our" branch if there is a conflict:

release_notes.txt merge=ours

This does not appear to be supported in Bitbucket cloud though. Could it be?