doc: fix HOWTORELEASE.rst
doc: fix HOWTORELEASE.rst

Remove last step, because it was merged already before (changed in
77cad3c4).

[ci skip]

txomon/pytest,tomviner/pytest,The-Compiler/pytest,tomviner/pytest,hackebrot/pytest,The-Compiler/pytest,RonnyPfannschmidt/pytest,alfredodeza/pytest,nicoddemus/pytest,nicoddemus/pytest,Akasurde/pytest,markshao/pytest,pytest-dev/pytest